KR100740099B1 - Setting apparatus of the soc reset period and the method thereof - Google Patents

Abstract

An apparatus and a method for setting an SOC(State Of Charge) reset period of a battery are provided to set a required SOC reset period by using a ratio of an OCV(Open Circuit Voltage) and an SOC with a reference value. In an apparatus for setting a reset period of an estimated SOC of a battery including at least one pack comprising a plurality of electric cells, a sensing part(100) measures information about a pack current, a pack voltage and cell temperature. An OCV calculation part(200) calculates an OCV voltage by using the information about the pack current, the pack voltage and the cell temperature of the battery. An SOC calculation part(300) calculates the estimated SOC. A calculation part(400) receives a first OCV and a first SOC, and receives a second OCV and a second SOC after a constant time, and then calculates a ratio of SOC variation to OCV variation by calculating the SOC variation and the OCV variation for the constant time. A control part(500) sets an SOC reset period by comparing the ratio and a reference value.

Description

Device and method for setting SOC reset period of battery {{SETTING APPARATUS OF THE SOC RESET PERIOD AND THE METHOD THEREOF}

1 is a graph showing the relationship between SOC and OCV.

2 is a diagram illustrating a configuration of an SOC reset interval setting apparatus according to an embodiment of the present invention.

3 is a flowchart illustrating a method for setting an SOC reset interval according to an embodiment of the present invention.

The present invention relates to a method for setting a section for resetting the state of charge of the battery. In particular, the present invention relates to a method for setting an SOC reset period by using data regarding a battery OCV (open circuit voltage) and a corresponding state of charge (SOC).

Automobiles using internal combustion engines that use gasoline or heavy oil as their main fuels have serious effects on pollution, such as air pollution. Therefore, in recent years, in order to reduce the occurrence of pollution, much efforts have been made in the development of electric vehicles or hybrid vehicles.

An electric vehicle is a vehicle using a battery engine operated by electric energy output from a battery. Such an electric vehicle uses no battery as a main power source because a plurality of secondary cells capable of charging and discharging are used as a pack has no exhaust gas and has a very small noise.

A hybrid vehicle, on the other hand, is an intermediate vehicle between an automobile using an internal combustion engine and an electric vehicle, and a vehicle using two or more power sources such as an internal combustion engine and a battery engine. At present, a hybrid vehicle of a hybrid type has been developed, such as using a fuel cell that directly generates an electric energy by chemical reaction while continuously supplying an internal combustion engine and hydrogen and oxygen, or uses a battery and a fuel cell.

In the vehicle using electric energy as described above, the performance of the battery directly affects the performance of the vehicle. Therefore, the performance of each battery cell must be excellent, and each battery cell is measured by measuring the voltage of each battery cell, the voltage and current of the entire battery, and the like. There is an urgent need for a battery management system (BMS) capable of efficiently managing charge and discharge of cells.

In particular, the battery management system needs to estimate the state of charge (SOC) of the battery, which is the charge available power and the output power that the battery can accept depending on the state of the SOC. (discharge available power) is different. If charging or discharging is performed by incorrectly judging these two power values, there is a risk of overcharge or overdischarge. Specifically, the battery should be charged and discharged within a range not exceeding different cutoff voltages during charging and discharging, and damage to the battery will occur if the battery is charged and discharged in an area exceeding the cutoff voltage. This cutoff voltage will depend on the charge available power and the discharge available power the battery can accept. Therefore, when the estimated SOC is not accurate, an error of acceptable power and discharge available power may occur, and the cutoff voltage may be changed due to this error, resulting in overcharge and Overdischarge may occur. The conventional SOC estimation algorithm has a disadvantage in that an error accumulates using a current integration method, and an SOC reset algorithm is used to compensate for this. However, for more accurate SOC estimation, it is necessary to set the SOC reset period according to the characteristics of the battery.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an apparatus and method for setting an SOC reset interval capable of setting an SOC reset interval for more accurate SOC estimation.

An SOC reset interval setting device for setting a reset interval of an estimated SOC of a battery, in which a plurality of battery cells are configured as one pack and including at least one pack, in accordance with an aspect of the present invention, the pack of the battery Sensing unit for measuring information about the current, pack voltage and cell temperature, OCV calculation unit for calculating the OCV voltage using information about the pack current, pack voltage and cell temperature of the battery, SOC calculation for calculating the estimated SOC The first OCV and the first SOC are input from the OCV calculator and the SOC calculator, and the second OCV and the second SOC are input after a predetermined time interval, and the SOC variable and the OCV variable are calculated during the predetermined time interval. And a calculator for calculating a ratio of the SOC variable to the OCV variable, and a controller configured to compare the ratio with a reference value and set an SOC reset period according to a comparison result.

According to another aspect of the invention, a SOC reset interval setting method for setting a reset interval of the estimated SOC of a battery comprising a plurality of battery cells consisting of one pack, including at least one pack, a) of the battery Measuring information regarding pack current, pack voltage, and cell temperature; b) calculating OCV voltage using information about pack current, pack voltage, and cell temperature of the battery; c) calculating the estimated SOC; Step, d) receiving a first OCV and a first SOC from the OCV calculating unit and the SOC calculating unit, respectively, receiving a second OCV and a second SOC after a predetermined time interval, and changing the SOC variable and the OCV variable during the predetermined time interval. Calculating a ratio of the SOC variable to the OCV variable, and e) comparing the ratio with a reference value and setting an SOC reset interval according to a comparison result.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

1 is a graph illustrating a relationship between a state of charge (SOC) and an open circuit voltage (OCV). OCV is the battery's output voltage when no load is connected to the battery's output.

As shown in FIG. 1, the amount of change in SOC corresponding to the amount of change in OCV is different for each OCV section. Therefore, when an error occurs in the calculated OCV value for each section, the range of the corresponding SOC error also varies for each section. As shown in FIG. 1, when the entire SOC section is set to 0% to 100%, the section A (0% to 40%), B (40% to 70%), and C (70% to 100%) Can be divided. Region B has a larger value than slopes A and C where the slope d is different. The slope d is a value obtained by dividing ΔSOC by ΔOCV, which is different for each section, and has the largest value in the section B. In the apparatus and method for setting an SOC reset interval according to an embodiment of the present invention, the interval B is referred to as an SOC intermediate region. When the B section is set as the SOC reset section, when the SOC is reset based on the measured OCV, when an error occurs in the calculated OCV, the corresponding SOC error may be very large. In addition, since the SOC is maintained in the area B when the SOC is managed due to the characteristics of the HEV system, the effectiveness of resetting the SOC included in the area B is less than that of other sections.

Hereinafter, an SOC reset period setting device according to an embodiment of the present invention will be described.

2 is a diagram illustrating a configuration of an SOC reset interval setting apparatus according to an embodiment of the present invention.

As shown in FIG. 2, the apparatus for setting a SOC reset interval according to an embodiment of the present invention includes a sensing unit, an OCV calculator 200, an SOC determiner, an operator 400, and a controller 500.

The sensing unit measures the total battery pack current Ip, the total battery pack voltage Vp, and the cell temperature Tc to the OCV calculator 200, and delivers the pack current Ip to the SOC calculator 300. do. The sensing unit may include a Hall CT, which measures the entire pack current Ip of the battery using a Hall element, and outputs an analog current signal corresponding to the measured current.

The OCV calculator 200 uses an internal resistance corresponding to the pack voltage Vp, the pack current Ip and the pack voltage Vp, the pack current Ip, and the cell temperature Tc input from the sensing unit. OCV (Vocv) is calculated. In general, an open circuit voltage (OCV) refers to a pack voltage Vp when a battery is in an open circuit state, that is, a pack voltage Vp in a no-load state. The OCV calculation unit 200 measures the pack voltage Vp measured by the sensing unit from data recording the relationship between the pack voltage Vp, the pack current Ip, and the cell temperature Tc and the internal resistance Ri calculated by the experiment. The internal resistance Ri corresponding to the pack current Ip and the cell temperature Tc can be detected and used. The OCV calculator 200 may include a database storing data recording the pack voltage Vp, the pack current Ip, and the relationship between the cell temperature Tc and the internal resistance Ri calculated by the experiment. . Specifically, OCV is calculated using Equation 1. In Equation 1, Vocv refers to an OCV value.

)을 이용하여 아래 수학식 2와 같이 추정 SOC를 산출한다. The SOC calculator 300 calculates an estimated SOC based on the pack current Ip and the charging efficiency received from the sensing unit. The actual charging efficiency of the specific battery

) To calculate the estimated SOC as shown in Equation 2 below.

는 충방전 전류로서 센싱부로부터 출력된 팩전류(Ip)이고,

는 배터리의 실제 충전효율이고,

는 총 배터리 용량(Total Amount of Charge)이다. here

Is the charge / discharge current and the pack current Ip output from the sensing unit,

Is the actual charging efficiency of the battery,

Is the total amount of charge.

) 및 OCV 변량(

)을 구한다. 이를 수학식 3과 같이 SOC 변량(

)을 OCV 변량(

)으로 나누어 기울기(S)를 산출한다.수학식 3에서 S는 SOC 변량(

)대 OCV 변량(

)에 대응하는 기울기이다.The calculating unit 400 measures the OCV variable vs. the SOC variable to calculate the slope. The calculation unit 400 calculates a change amount of the OCV value and the SOC value output from the OCV calculator 200 and the SOC calculator 300 at regular intervals. At this time, the constant time interval is a time that can be arbitrarily set, and a shorter time interval can be set to obtain more accurate gradient data. Specifically, the operation unit 400 first measures the first SOC (SOC1) value and the first OCV (Vocv1) value measured at a predetermined time interval from the second SOC (SOC2) value and the second OCV (Vocv2) value. By subtracting each,

) And OCV variance (

) This is expressed as SOC variance (

) To the OCV variance (

And calculate the slope (S), where S is the SOC variance (

) Vs OCV Variables

Is the slope corresponding to

The controller 500 receives the OCV and the SOC from the OCV calculator 200 and the SOC calculator 300, respectively, and receives the slope S from the calculator 400.

The controller 500 compares the input slope S with a reference value. Set the SOC reset section according to the comparison result. Specifically, when the slope S is smaller than the reference value, the section may be set as the SOC reset section. If the slope S is greater than the reference value, the section is excluded from the SOC reset section. In general, the slope of the SOC B region (FIG. 1) has a larger value than other sections A and C. FIG. The SOC reset interval setting device according to the embodiment of the present invention is less than or equal to the lowest slope in the SOC B region. The control unit 500 detects a section that is less than the reference value as a result of the comparison with the reference value, and sets the SOC reset section. The controller 500 may set a specific SOC belonging to the set SOC reset period as the reset SOC. The controller 500 may include a database storing the input OVC, SOC, slope S, and SOC reset interval setting result.

3 is a flowchart illustrating a method for setting an SOC reset interval according to an embodiment of the present invention.

As shown in FIG. 3, the sensing unit measures the total battery pack current Ip, the total battery pack voltage Vp, and the cell temperature Tc, transfers the measured data to the OCV calculator 200, and the battery. The entire pack current Ip is transmitted to the SOC calculator 300 (S100).

The OCV calculator 200 calculates the OCV using the pack voltage Vp and the pack current Ip received from the sensing unit, and an internal resistance corresponding thereto (S200).

The SOC calculator 300 calculates an estimated SOC based on the pack current Ip and the charging efficiency received from the sensing unit (S300).

The calculating unit 400 measures the OCV variable vs. the SOC variable and calculates the slope S (S400). The calculation unit 400 calculates a change amount of the OCV value and the SOC value output from the OCV calculator 200 and the SOC calculator 300 at regular time intervals. Specifically, the operation unit 400 obtains the variance of SOC and OCV by first subtracting the measured SOC value and OCV value from the measured SOC value and OCV value at regular intervals. The slope S is calculated by dividing the change amount of the SOC value by the change amount of the OCV value.

The controller 500 receives OCV and SOC from the OCV calculator 200 and the SOC calculator 300, respectively, and receives the slope S output from the calculator 400 (S500). The controller 500 compares the slope S with the reference value Sref (S600). As a result of the comparison in operation S600, when the slope S is smaller than the reference value Sref, the interval is set as the SOC reset interval (S610). As a result of the comparison in step S600, if the reference value Sref or more, the section is excluded from the SOC reset section (S620). The controller 500 stores the input OCV, SOC, and the set SOC reset period (S700). By repeating this, the SOC reset section is set among the entire SOC sections.

As described above, the apparatus and the method for setting the SOC reset interval according to the embodiment of the present invention calculate the variances of the OCV and the SOC, measure the slope S using the same, and set the SOC reset interval. By using the SOC reset period set as described above, the estimated SOC error can be reduced.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an aspect of the present invention, there is provided an apparatus and method for setting an SOC reset interval for setting an SOC reset interval necessary to reduce an error of an estimated SOC.

According to another feature of the present invention, there is provided an apparatus and method for setting a SOC reset interval that can set the SOC reset interval of the battery pack using the OCV of the battery.

Claims (11)

In the SOC reset interval setting device for setting a reset interval of the estimated SOC of a battery comprising a plurality of battery cells consisting of one pack, at least one pack, A sensing unit for measuring information regarding a pack current, a pack voltage, and a cell temperature of the battery; An OCV calculator configured to calculate an OCV voltage using information on a pack current, a pack voltage, and a cell temperature of the battery; An SOC calculator for calculating the estimated SOC; The first OCV and the first SOC are input from the OCV calculator and the SOC calculator, respectively, the second OCV and the second SOC are input after a predetermined time interval, and the SOC variable and the OCV variable are calculated during the predetermined time interval. An operation unit for calculating a ratio of the SOC variable to the OCV variable, and Control unit for setting the SOC reset interval according to the comparison result by comparing the ratio and the reference value SOC reset interval setting device comprising a. The method of claim 1, If the ratio is less than the reference value, the controller sets the interval between the first SOC and the second SOC as an SOC reset interval, and if the ratio is greater than or equal to the reference value, the interval between the first SOC and the second SOC. SOC reset interval setting device which does not set the value as the SOC reset interval. The method of claim 2, And the ratio is a value obtained by dividing the SOC variable by the OCV variable. The method of claim 3, And the reference value is smaller than the minimum value of the ratio in the middle region of the SOC. The method of claim 4, wherein And a middle region of the SOC is an interval corresponding to SOC 70% to SOC 70%. The method according to any one of claims 1 to 5, The OCV calculation unit, And an internal resistance corresponding to the pack voltage, the pack current, and the cell temperature, and calculating the OCV by compensating for the voltage generated by the internal resistance to the pack voltage. The method of claim 6, The SOC calculation unit, And an SOC reset section setting device that estimates the SOC by integrating the pack current. In the SOC reset interval setting method for setting a reset interval of the estimated SOC of a battery comprising a plurality of battery cells consisting of one pack, at least one pack, a) measuring information regarding a pack current, a pack voltage, and a cell temperature of the battery; b) calculating an OCV voltage using information on the pack current, pack voltage, and cell temperature of the battery; c) calculating the estimated SOC, d) receiving a first OCV and a first SOC from the OCV calculating unit and the SOC calculating unit, and receiving a second OCV and a second SOC after a predetermined time interval, and calculating an SOC variable and an OCV variable during the predetermined time interval. Calculating a ratio of the SOC variable to the OCV variable, and e) comparing the ratio with the reference value and setting the SOC reset interval according to the comparison result SOC reset interval setting method comprising a. The method of claim 8, Step e), If the ratio is smaller than the reference value, the section between the first SOC and the second SOC is set as an SOC reset section. If the ratio is equal to or greater than the reference value, the section between the first SOC and the second SOC is SOC reset. How to set SOC reset section not set to section. The method of claim 9, And the ratio is a value obtained by dividing the SOC variable by the OCV variable. The method of claim 10, And the reference value is smaller than the minimum value of the ratio in the middle region of the SOC.

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