KR20200038914A - Method for estimating state of charge(soc) - Google Patents

Abstract

The present invention relates to a method for estimating a state of charge of an energy storage device. More specifically, provided is the method for estimating a state of charge of an energy storage device, which estimates a state of charge of an energy storage device through a voltage modeling technique using different parameters in accordance with a state of charge/discharge.

Description

Energy storage device charging state estimation method {METHOD FOR ESTIMATING STATE OF CHARGE (SOC)}

The present invention relates to a method for estimating a state of charge of an energy storage device, and more specifically, to estimate an accurate state of charge of an energy storage device using a different state of charge (SOC) parameter according to a state of charge / discharge when using a voltage modeling technique. It relates to a method for estimating the state of charge of the energy storage device.

With the development of the industry, the demand for electric power is increasing, and the gap in electric power usage between day and night, season, and day is gradually widening. For this reason, many technologies for reducing peak loads by utilizing the surplus power of the system have been rapidly developed.

A representative of these technologies is an energy storage system (ESS) that stores excess power of the system in a battery or supplies insufficient power of the system from a battery.

In addition, the ESS is formed of a plurality of batteries, and a general battery efficiently controls charging or discharging of the battery by configuring a battery management system (BMS) therein.

In order to maintain the battery life for a long time and use it safely, it must be operated within the proper charging range of the battery, and the battery life varies greatly depending on the number of charge / discharge cycles.

Therefore, it is important to grasp the state of the battery by accurately estimating the state of charge (SOC) by measuring the current, voltage, and temperature of the battery through the BMS.

The method for estimating the state of charge (SOC) can be broadly classified into four categories, a current integration method for integrating charge / discharge currents, an electrochemical model technique for displaying the chemical reaction inside a cell in molecular units, and a battery operating time and It uses a mathematical method that expresses the dynamic behavior of the SOC in a purely mathematical empirical formula, and a voltage modeling technique using the relationship between the Open Circuit Voltage (OCV) and the SOC (SOC). To estimate the state of charge (SOC).

On the other hand, the electrochemical model technique has a disadvantage of being vulnerable to temperature changes, and the mathematical technique has a problem that the production cost increases due to the complexity of the algorithm in the BMS.

Therefore, the method of estimating the state of charge (SOC) of a general ESS uses the current integration method and the voltage modeling technique together. The voltage modeling technique also has less accuracy when charging / discharging, and thus has a higher dependence on the current integration method than the voltage modeling technique.

However, since the current integration method also accumulates charge / discharge currents using an integrator, there is a problem in that the error of the current accumulation value by the current sensor having an incorrect initial value and a high error rate during long time use becomes very large.

In addition, in order to estimate the aging state (SOH) for battery life prediction, when estimating the aging state (SOH) based on the charged state (SOC) estimated through the current integration method, the incorrect initial value and When using the battery for a long time, the battery cell is degraded due to a large error in the current accumulated value by the current sensor, and thus a problem of failing to accurately estimate the capacity compared to the changed capacity occurs.

Therefore, there is a need to develop a technology capable of accurately estimating the state of charge (SOC) of the ESS even when used for a long time by increasing the dependency of the voltage modeling technique rather than the current integration method.

(Patent Document 1) KR10-1227417 B

The present invention provides a method for estimating the state of charge of an energy storage device that improves the accuracy of the state of charge of an energy storage device estimated by a voltage modeling technique.

The method for estimating the state of charge (SOC) of the energy storage device (ESS) according to an embodiment of the present invention includes a method for estimating the state of charge (SOC) of the energy storage device (ESS). State measurement step of measuring, state of charge (SOC) estimation step of estimating the state of charge (SOC) based on each method by applying the current, voltage and temperature measured in the state measurement step to the current integration method and voltage modeling technique, the charging An error range comparison step of comparing whether the difference between the charging state of the current integration method estimated in the state (SOC) estimation step and the charging state of the voltage modeling method exceeds a predetermined error range, and the charging state of the current integration method in the error range comparison step ( SOC) and the state of charge of the voltage modeling technique (SOC) exceeds a predetermined error range, the state of charge of the current integration method and the state of charge of the voltage modeling technique It is configured to apply a predetermined weight including calculating final state of charge (SOC) and calculating the final state of charge (SOC).

In the charging state (SOC) estimating step, the current charging state (SOC) estimating step and the state measuring step of estimating the charging state (SOC) of the energy storage device by applying the current measured in the state measuring step to the current integration method It comprises a voltage charging state (SOC) estimation step of estimating the state of charge (SOC) of the energy storage device by applying the measured current, voltage and temperature to the voltage modeling technique.

The error range comparison step may include: an estimation number comparison step of comparing whether the current charging state (SOC) estimation step exceeds a predetermined estimation number; It is configured to further include, when the current state of charge (SOC) estimation step exceeds a predetermined number of times, the final state of charge (SOC) calculation step is performed.

Energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention, a state measurement unit for measuring the current, voltage and temperature of the energy storage device (ESS), the current measured by the state measurement unit, A charging state (SOC) estimator which estimates a charging state (SOC) based on each method by applying voltage and temperature to a current integration method and a voltage modeling technique, and the charging state of the current integration method estimated by the charging state (SOC) estimator ( SOC) and an error range comparator for comparing whether the difference between the SOC of the voltage modeling technique exceeds a predetermined error range, and the difference between the charging state of the current integration method and the charging state of the voltage modeling technique in the error range comparison unit If it exceeds the error range of, the final charging state (S) for calculating the final charging state (SOC) by applying a predetermined weight to the charging state of the current integration method and the charging state of the voltage modeling technique OC) It comprises a memory for storing each of the charged state (SOC) estimated by the calculation unit and the state of charge (SOC) estimation unit.

The state of charge (SOC) estimator includes a current accumulator for estimating a state of charge (SOC) of the energy storage device by applying the current measured by the state measurement unit to a current integration method, and the current, voltage, and current measured by the state measurement unit. It includes a voltage modeling unit that estimates the state of charge (SOC) of the energy storage device by applying temperature to the voltage modeling technique.

The voltage modeling unit, a charge / discharge determination unit for determining whether it is in a charge state or a discharge state based on the current and voltage measured by the state measurement unit, and a charging state (SOC) based on the state determined by the charge / discharge determination unit ) Voltage charging state (SOC) for estimating the charging state (SOC) of the energy storage device (ESS) based on the parameter derivation unit deriving the parameter and the charging state (SOC) parameter derived from the parameter derivation unit ) It comprises an estimation unit.

The parameter derivation unit derives a state of charge (SOC) parameter based on the temperature measured by the state measurement unit and the state of charge (SOC) estimated in the previous estimation cycle stored in the memory.

The error range comparison unit is further configured to further include an estimation frequency comparison unit for comparing whether the estimated number of charge state (SOC) performed by the current integration unit exceeds a predetermined estimation number.

The method for estimating the state of charge of the energy storage device according to an embodiment of the present invention derives a different state of charge (SOC) parameter according to the state of charge / discharge, so that a more accurate state of charge of the energy storage device can be estimated.

1 is a flow chart of an energy storage device (ESS) charging state (SOC) estimation method according to an embodiment of the present invention.
Figure 2 is a graph according to the current amount of the maximum error rate of the charging state (SOC) applied to an embodiment of the present invention and the maximum error rate of the charging state (SOC) applying the conventional estimation method.
3 is a flow chart of an energy storage device (ESS) charging state (SOC) estimation method according to this embodiment.
4 is a flow chart of a state of charge (SOC) estimation of the energy storage device (ESS) charging state (SOC) estimation method according to this embodiment of the present invention.
5 is a block diagram of an energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention.
6 is a configuration diagram of an SOC estimator in an energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention.

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 to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are attached to similar parts throughout the specification.

<Example 1>

Next, an energy storage device (ESS) charging state (SOC) estimation method according to an embodiment of the present invention will be described.

The energy storage device (ESS) charging state (SOC) estimation method of the present invention derives different charging state (SOC) parameters according to the charging / discharging state and accurately charging based on the derived charging state (SOC) parameters. Allow the state (SOC) to be estimated.

1 is a flow chart of an energy storage device (ESS) charging state (SOC) estimation method according to an embodiment of the present invention.

Referring to Figure 1, the energy storage device (ESS) charging state (SOC) estimation method according to an embodiment of the present invention first measures the current, voltage and temperature of the energy storage device (ESS) (first step / below , State measurement step: S110), it is determined whether the state of charge or discharge based on the measured current and voltage (second step / less, charge / discharge judgment step: S120).

 A charging state (SOC) parameter is derived based on the charging state or the discharging state determined in the charging / discharging determination step (S120) (third step / hereinafter, parameter derivation step: S130), and the derived charging state Estimating the state of charge (SOC) of the energy storage device based on the (SOC) parameter (step 4 / hereinafter, the state of charge (SOC) estimation step: S140).

In addition, the entire step is repeated with a predetermined estimation cycle, which is for estimating an accurate state of charge (SOC). Here, the predetermined estimation period may be set to 30 seconds as an example, but is not limited thereto.

Each step of the energy storage device (ESS) charging state (SOC) estimation method will be described in more detail below.

The state measurement step (S110) measures the current, voltage and temperature of the energy storage device (ESS), and more specifically, measures the current, voltage and temperature of the battery rack in the energy storage device (ESS).

In addition, a general energy storage device (ESS) is formed by providing a plurality of battery racks, which are formed by stacking battery modules composed of a plurality of battery cells.

Therefore, the current, voltage and temperature of the measured battery rack are collected by the battery module, and the current, voltage and temperature of each collected battery module are transferred to the battery rack for final collection. It is calculated after.

In addition, the estimation cycle is changed according to the state of charge (SOC). In general, the estimation error of the state of charge (SOC) is increased for the low state of charge (SOC) and the high state of charge (SOC).

Therefore, the charging state (SOC) of 0 to 10 and 90 to 100% is changed in a cycle so that the charging state (SOC) can be estimated in 1% increments, and the charging state (SOC) of 10 to 90% is 20%. By changing the cycle so that the state of charge (SOC) can be estimated in units, an efficient and accurate value can be estimated.

In addition, the charge / discharge determination step (S120) determines the charge / discharge state based on the current and voltage measured in the state measurement step (S110).

The general charge and discharge states are determined by the polarization voltage inside the battery, and the polarity of the polarization voltage is determined by accumulating values according to the current direction.

When the current has a discharge (-) polarity, a (-) value is accumulated in the polarization voltage, and when the current is a charge (+) polarity, a (+) value is accumulated in the polarization voltage.

In addition, when there is no current flow, the value of the polarization voltage converges to zero. When the value of the polarization voltage is 0, the state of charge (SOC) is maintained at the last polarity immediately before.

Therefore, when determining the state of charge and discharge, if it is simply determined according to the direction of the current, the state inside the battery cannot be sufficiently reflected.

For example, when charging with a current of 8A for 15 minutes and then discharging with 2A for 4 seconds, the final direction of the current is discharged, but (S120) inside the battery appears closer to charging.

As described above, when determining the state of charge and discharge of the battery, it can be determined by considering the magnitude and duration of the current flowing for a predetermined time.

In addition, the parameter derivation step (S130) derives parameters according to the charge state or the discharge state determined in the charge / discharge determination step (S120).

The above parameter is a variable that appears in the characteristics of the RC circuit. In general, since the battery is a substance having chemical characteristics, in order to analyze it, an RC circuit having the same characteristics as the battery is constructed, and the circuit is analyzed to find out the performance of the battery. see.

Modeling using the R-C circuit means that the more complex the circuit is, the more difficult it is to analyze, so that the characteristics of the battery are represented by a circuit composed of a resistor and a capacitor.

In addition, in a battery model modeling a battery as an R-C circuit, information about an internal component value of the R-C circuit that changes according to temperature and state of charge (SOC) is stored.

Therefore, the RC circuit consists of the most basic elements, the battery internal resistance component (R0) and the polarization components (R1, C1) that change according to the temperature and the state of charge (SOC), which are called parameters. Shows.

(Equation 1)

Here, Vt (t) and i (t) are the voltage and current measured in the R-C circuit at time t, V1 is the polarization voltage, and v (t) is the value to compensate for the measurement error.

In addition, the state variable equation defined by the first order differential relationship of V1 (t) means the voltage applied to the RC stage at time t (that is, V1 (t) means the voltage applied to R1 and C1 stages), w1 (t) is a value for compensating for measurement error.

On the other hand, the state of charge (SOC) parameters of each parameter value (internal component value / (internal resistance (R0), resistance (R1), resistance (R1), capacitor (C1)) updated by temperature and state of charge (SOC)) It is composed of a table and derives each parameter value using the measured temperature and the state of charge (SOC) estimated in the previous estimation cycle.

In addition, the state of charge (SOC) parameter table is configured separately for each state of charge and discharge, thereby increasing the accuracy that was reduced during charge / discharge.

If the current estimation period is the first estimation period, the charging state (SOC) is first estimated by the current integration method and the previously estimated charging state (SOC) is set as the charging state (SOC) of the previous estimation period.

In addition, the state of charge (SOC) estimation step (S140) estimates the state of charge (SOC) of the energy storage device based on the state of charge (SOC) parameter derived in the parameter derivation step (S130).

In one embodiment of the present invention, a voltage modeling technique is used to estimate the state of charge (SOC), which has a good linear relationship between the open circuit voltage (OCV) and the state of charge (SOC). The state of charge (SOC) can be easily estimated using the table shown.

However, since the open circuit voltage (OCV) is a voltage when discharging or charging is not performed (when no current is applied), after discharging or charging is performed, after several tens of minutes or hours, the positive and negative electrodes The voltage at both ends must be measured.

Therefore, the method of calculating the open circuit voltage (OCV) is calculated by subtracting the voltage dropped from the polarization voltage and internal component values generated during charging / discharging from the voltage measured in the battery pack, which is expressed by (Equation 2).

 (Equation 2) Open circuit voltage (OCV) = Voltage of the battery pack-Polarization voltage-Dropped voltage

Here, the polarization voltage and the enhanced voltage are calculated by putting the state of charge (SOC) parameter derived in the parameter derivation step (S130) into (Equation 1).

In addition, if the calculated open circuit voltage OCV is matched to the correlation table between the charging state SOC and the open circuit voltage OCV, the charging state SOC can be easily derived.

As described above, it can be seen that the charging state SOC calculated with other parameters according to the charging / discharging state has a lower error rate than the conventional charging state SOC, as shown in FIG. 2.

2 is a graph of the current amount of the maximum error rate of the charging state (SOC) applying the embodiment of the present invention and the maximum error rate of the charging state (SOC) applying the conventional estimation method.

Referring to FIG. 2, the dotted line is the error rate of the charged state (SOC) calculated by always using the same charged state (SOC) parameter without considering the charge / discharge state according to the magnitude of the current, and the solid line is the charged state or discharge It means that the error rate of the charged state (SOC) calculated using the different charged state (SOC) parameters according to the state can be confirmed that the error rate of the solid line is significantly reduced than the dotted line.

<Example 2>

Next, an energy storage device (ESS) charging state (SOC) estimation method according to this embodiment of the present invention will be described.

The method for estimating the state of charge (SOC) of the energy storage device (ESS) of the present invention estimates the correct state of charge (SOC) by changing the weight according to the error range between the state of charge (SOC) estimated based on the current integration method and the voltage modeling technique. To be able to.

3 is a flowchart of an energy storage device (ESS) charging state (SOC) estimation method according to this embodiment.

Referring to Figure 3, the method of manufacturing a battery cell according to this embodiment of the present invention first measures the current, voltage and temperature of the energy storage device (state measurement step: S310), the measured current, voltage and temperature and current integration method And a voltage modeling technique to estimate each state of charge (SOC) (step of estimating state of charge (SOC): S320).

Compare whether the difference between the charging state of the current integration method estimated in the charging state (SOC) estimation step (S320) and the charging state of the voltage modeling method exceeds a predetermined error range (error range comparison step: S330), and charging the current integration method When the difference between the state (SOC) and the charging state (SOC) of the voltage modeling technique exceeds a predetermined error range, a final charging state (SOC) is applied by applying a predetermined weight to the charging state of the current integration method and the charging state of the voltage modeling technique. ) Is calculated (step of calculating the final state of charge (SOC): S340).

Each step of the energy storage device (ESS) state of charge (SOC) estimation method will be described in more detail below.

The state measurement step (S110) measures the current, voltage and temperature of the energy storage device (ESS), and more specifically, measures the current, voltage and temperature of the battery rack in the energy storage device (ESS).

In addition, a general energy storage device (ESS) is formed by providing a plurality of battery racks, which are formed by stacking battery modules composed of a plurality of battery cells.

Therefore, the current, voltage, and temperature of the measured battery rack are collected by the battery module, and the current, voltage, and temperature of each collected battery module are transferred to the battery rack and collected. This is a derived value.

In addition, the entire step is repeated at a predetermined estimation cycle, which is to estimate an accurate state of charge (SOC). Here, the predetermined estimation period may be set to 30 seconds as an example, but is not limited thereto.

In addition, the estimation cycle is changed according to the state of charge (SOC). In general, the estimation error of the state of charge (SOC) is increased for the low state of charge (SOC) and the high state of charge (SOC).

Therefore, the charging state (SOC) of 0 to 10 and 90 to 100% is changed in a cycle so that the charging state (SOC) can be estimated in 1% increments, and the charging state (SOC) of 10 to 90% is 20%. By changing the cycle so that the state of charge (SOC) can be estimated in units, an efficient and accurate value can be estimated.

In addition, the state of charge (SOC) estimation step (S320) estimates each state of charge (SOC) by using the current, voltage and temperature and current integration method and voltage modeling technique measured in the state measurement step (S310).

In addition, the charging state (SOC) estimation step will be described in more detail with reference to FIG. 4.

4 is a flow chart of a state of charge (SOC) estimation of the energy storage device (ESS) charging state (SOC) estimation method according to this embodiment of the present invention.

The charging state (SOC) estimation step estimates the charging state (SOC) of the energy storage device by applying the current measured in the state measuring step (S320) to the current integration method (current charging state (SOC) estimation step: S321) , Estimating the state of charge (SOC) of the energy storage device by applying the current, voltage and temperature measured in the state measurement step (S320) to the voltage modeling technique (voltage state of charge (SOC) estimation step: S322).

In more detail, the current charging state (SOC) estimating step (S321) is a method for estimating the charging state (SOC) of the energy storage device using the current integration method, measured in the state measuring step (S320). The state of charge (SOC) is estimated based on the current.

In addition, since the current integration method is simply a method of estimating only with current, the algorithm is simple and the state of charge (SOC) can be quickly estimated using this, which is expressed by (Equation 3).

(Equation 3) SOC = SOC_i- (i dt) / (Nominal Capacity)

Here, SOC_i is the state of charge (SOC) of the previous estimation cycle, the nominal capacity is the amount of current that can be generally used at room temperature as the nominal capacity, and ∫i dt is the amount of current accumulated for a predetermined time.

The voltage charging state (SOC) estimating step (S322) is a method of estimating the charging state (SOC) of the energy storage device by applying it to a voltage modeling technique, and the current, voltage and temperature measured in the state measuring step (S320) Based on this, the state of charge (SOC) is estimated.

In addition, in the voltage modeling technique, the state of charge (SOC) is estimated based on the open circuit voltage (OCV), so the accuracy during charging / discharging is reduced. Here, the open circuit voltage (OCV) is a voltage when no discharge or charging is performed (when no current is applied).

As a solution to this, different charging state (SOC) parameters are tabulated according to the state of charge and discharge so that the state of charge (SOC) for each state can be estimated.

Further, if the voltage charging state (SOC) estimation step (S322) is described in more detail, first, it is determined whether the battery is in a charged state or a discharged state, and the temperature measured in the state measurement step (S320) and the previous measurement cycle. The state of charge (SOC) parameter is derived based on the measured state of charge (SOC). Here, the state of charge (SOC) parameter has a different value depending on the state of charge / discharge of the battery.

If the parameters derived according to the state of the battery are calculated by putting in (Equation 1), the polarization voltage and the dropped voltage required for (Equation 2) can be calculated.

Calculating the open circuit voltage (OCV) through (Equation 2), and matching the calculated open circuit voltage (OCV) to the table between the charging state (SOC) and the open circuit voltage (OCV), the charging state (SOC) It can be easily derived.

Further, in the error range comparison step (S330), the difference between the charging state (SOC) of the current integration method estimated in the charging state (SOC) estimation step (S320) and the charging state (SOC) of the voltage modeling technique is a predetermined error range. Compare if exceeded.

It is estimated that the current charging state (SOC) estimated in the current charging state (SOC) estimating step (S321) is based on the charging state (SOC) calculated in the previous estimation cycle, and is based only on the current value measured by the current sensor. This is because the accuracy of the charging state (SOC) decreases because the error rate of the current sensor, which has a larger error rate than the voltage sensor, is accumulated.

Therefore, the difference between the charging state (SOC) of the voltage modeling technique with a relatively low error rate over time and the charging state (SOC) of the current integration method in which the error rate increases with time is calculated to compare whether the difference exceeds a predetermined range. do.

Here, it is preferable to set the predetermined range to a value that exceeds 2 to 3 times larger than the generally occurring error range.

In addition, the error range comparison step (S330) includes: comparing the estimated number of times whether the current charging state (SOC) estimation step exceeds a predetermined estimation number; As it is further configured to include, it is possible to prevent a problem caused by a temporary error.

Accordingly, when the current charging state (SOC) estimation step exceeds a predetermined number of times, the final charging state (SOC) calculation step can be performed, and if the current charging state (SOC) estimation step is a predetermined estimation number If it is less than, it is assumed that a temporary error has occurred and the state measurement step (S310) is performed again. Here, the predetermined number of times is the number of times the error value is generally increased when the current integration method is used, which means that the reliability of the charged state (SOC) estimated by the current integration method is significantly lowered.

In addition, in the final charging state (SOC) calculation step (S340), the difference between the charging state (SOC) of the current integration method and the charging state (SOC) of the voltage modeling method in the error range comparison step (S330) is a predetermined error range. If it exceeds, the final charging state (SOC) is calculated by applying predetermined weights to the charging state of the current integration method and the charging state of the voltage modeling technique.

For example, if the initial ratio of the charging state (SOC) of the current integration method and the charging state (SOC) of the voltage modeling method is 2: 1, the ratio is changed to 1: 4, and the charging state of the current integration method (SOC) The weight for is calculated as 1/5, and the weight for SOC in the voltage modeling technique is calculated as 4/5.

Therefore, when the state of charge (SOC) of the current integration method is 90 (%) and the state of charge (SOC) of the voltage modeling technique is 60 (%), the final SOC (%) = 90 * (1/5) + (60) * (4/5), the final state of charge (SOC) is calculated as 66 (%).

This is because the voltage modeling technique also generates an error rate, so that an accurate charging state (SOC) can be calculated by adjusting the ratio of the charging state (SOC) of the current integration method.

<Example 3>

Next, an energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention will be described.

The energy storage device (ESS) charging state (SOC) estimating device of the present invention estimates an accurate charging state (SOC) according to the charging or discharging state through a voltage modeling technique, so that an accurate charging state (SOC) is calculated over time. Make it possible.

5 is a configuration diagram of an energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention.

Referring to FIG. 5, the energy storage device (ESS) charging state (SOC) estimation device 100 according to an embodiment of the present invention is a state measurement unit 200 that measures current, voltage, and temperature of the energy storage device ESS ), The charging state (SOC) estimator 300, which estimates each charging state (SOC) through the current integration method and the voltage modeling technique based on the current, voltage and temperature measured by the state measuring unit 200, charging The error range comparison unit 400 compares whether the difference between the charging state (SOC) of the current integration method and the charging state (SOC) of the voltage modeling method estimated by the state (SOC) estimator 300 exceeds a predetermined error range. When the difference between the charging state of the current integration method and the charging state of the voltage modeling method exceeds a predetermined error range in the range comparison unit 400, a predetermined weight is applied to the charging state of the current integration method and the charging state of the voltage modeling technique. The final charging state (SOC) Shipping is configured to include a memory 600 to store each state of charge (SOC) from the estimated final state of charge (SOC) calculation unit 500 and the state of charge (SOC) estimator 300. The

The energy storage device (ESS) state of charge (SOC) estimation device 100 may be configured inside or outside the battery BMS.

In addition, each configuration of the energy storage device (ESS) state of charge (SOC) estimation device will be described in more detail below.

The state measuring unit 200 measures the current, voltage and temperature of the energy storage device (ESS).

In more detail, the state measurement unit 200 commands each battery cell to measure current, voltage, and temperature through a temperature sensor, and the current, voltage, and temperature of each measured battery cell are collected and transmitted. Control.

In addition, the state measurement unit 200 is performed every predetermined estimation period, which changes according to the state of charge (SOC).

In general, a low state of charge (SOC) and a high state of charge (SOC) have a high estimated error in the state of charge (SOC). As an example, the state of charge (SOC) of 0 to 10 and 90 to 100% is 1%. The estimated cycle is changed so that the state of charge (SOC) is estimated. In addition, the estimated cycle is changed so that the state of charge (SOC) is estimated in 20% increments. It can be estimated.

The state of charge (SOC) estimator 300 estimates each state of charge (SOC) by applying the current, voltage, and temperature measured by the state measurement unit 200 to a current integration method and a voltage modeling technique.

In addition, the state of charge (SOC) estimator 300 will be described in detail with reference to FIG. 6.

6 is a configuration diagram of an SOC estimator in an energy storage device (ESS) charging state (SOC) estimation device according to an embodiment of the present invention.

Referring to FIG. 6, the state of charge (SOC) estimator 300 applies a current measured by the state measurement unit 200 to a current integration method to estimate a state of charge (SOC) of an energy storage device. It comprises a voltage modeling unit 320 for estimating the state of charge (SOC) of the energy storage device by applying the current, voltage and temperature measured by the state measurement unit 200 and the voltage modeling technique.

In addition, the current accumulating unit 310 has a current accumulation method algorithm as shown in Equation (3) previously stored, so that the state of charge of the energy storage device (SOC) is based on the current measured by the state measuring unit 200. To estimate.

In addition, the estimated state of charge (SOC) is stored in the memory 600 to be used for the next estimation cycle and the first estimation cycle in the voltage modeling unit 320.

In addition, the voltage modeling unit 320 has previously stored algorithms of voltage modeling techniques such as (Expression 1) and (Expression 2), and applies the current, voltage, and temperature measured by the state measurement unit 200. To estimate the state of charge (SOC).

Referring to FIG. 6, the voltage modeling unit 320 is a charge / discharge determination unit 321 that determines whether it is in a charged or discharged state based on the current and voltage measured by the state measurement unit 200. The charging state (SOC) parameter derived from the parameter derivation unit 322 and the parameter derivation unit 323 for deriving the charging state (SOC) parameter based on the state determined by the / discharge determining unit 321 And a voltage charging state (SOC) estimating unit 324 for estimating the charging state (SOC) of the energy storage device ESS based on the variable.

In more detail, the charge / discharge determination unit 321 accumulates polarization voltages generated during charge / discharge, and determines whether the state is charged or discharged according to the polarity of the accumulated values.

In addition, the parameter derivation unit 323 is determined by the charge / discharge determination unit 321 based on the temperature measured by the state measurement unit 200 and the state of charge (SOC) estimated in the previous estimation cycle. Depending on the state of the battery, different charge state (SOC) parameters are derived. Here, the state of charge (SOC) parameter has different tables for each state of charge and discharge, so that an accurate state of charge (SOC) can be estimated.

Here, the charge state and the discharge state table are pre-stored in the memory 600.

In addition, since the voltage charging state (SOC) estimator 324 includes the algorithms of Equations (1) and (2), the open circuit voltage is based on the parameters derived from the parameter derivation unit 323. Calculate (OCV) and match the calculated open circuit voltage (OCV) to the correlation table between the charge state (SOC) and the open circuit voltage (OCV) to estimate the voltage charge state (SOC). Here, a correlation table between the state of charge (SOC) and the open circuit voltage (OCV) is pre-stored in the memory 600.

In addition, the error range comparison unit 400 is a difference between the charging state (SOC) of the current integration method and the charging state (SOC) of the voltage modeling method estimated by the charging state (SOC) estimating unit 300 is a predetermined error range. Compare if exceeded.

Here, the SOC difference calculating unit calculates a difference between the charging state (SOC) of the current integration method estimated by the charging state (SOC) estimating unit 300 and the charging state (SOC) of the voltage modeling technique; It is configured to further include.

In addition, the estimated count comparison unit for comparing whether the number of charge state (SOC) estimation performed by the current integration unit 310 exceeds a predetermined estimation number; It is further configured to prevent the adjustment of the state of charge (SOC) weight due to a temporary error.

In addition, when the difference between the state of charge of the current integration method and the state of charge of the voltage modeling method exceeds the predetermined error range, the final state of charge (SOC) calculation unit 500 in the error range comparison unit 400 The final charging state (SOC) is calculated by applying a predetermined weight to the charging state of the integration method and the charging state of the voltage modeling technique.

The final state of charge (SOC) calculation unit 500 is pre-stored in an algorithm for calculating the final state of charge (SOC) by applying weights, and the state of charge (SOC) estimated by the current integration unit 310 and the The charging state (SOC) estimated by the voltage modeling unit 320 is changed and applied to a predetermined weight to calculate a final charging state (SOC).

In addition, the memory 600 stores each state of charge (SOC) estimated by the state of charge (SOC) estimator 300, and the state of charge and discharge state tables used in the parameter derivation unit 322 This is already saved.

In addition, a correlation table between the state of charge (SOC) and the open circuit voltage (OCV) used in the SOC estimator 323 is pre-stored, and the table has the same value regardless of the state of charge and discharge of the battery. use.

This is because the open circuit voltage (OCV) accumulates voltage values for charge and discharge states, so the average value of the charge and discharge states is used.

On the other hand, although the technical spirit of the present invention has been described in detail according to the above embodiment, it should be noted that the above embodiment is for the purpose of explanation and not for the limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical spirit of the present invention.

100: energy storage device charge state estimation device
200: state measuring unit
300: SOC estimation unit
310: current integration unit
320: voltage modeling unit
321: charge / discharge judgment unit
322: parameter derivation unit
323: SOC estimation unit
400: error range comparison unit
500: final SOC calculation unit
600: memory

Claims (8)

In the method for estimating the state of charge (SOC) of the energy storage device (ESS),
A state measurement step of measuring current, voltage and temperature of the energy storage device;
A charging state (SOC) estimation step of estimating a charging state (SOC) based on each method by applying the current, voltage and temperature measured in the state measuring step to a current integration method and a voltage modeling technique;
An error range comparison step of comparing whether a difference between the charging state of the current integration method and the charging state of the voltage modeling method estimated in the charging state (SOC) estimation step exceeds a predetermined error range; And
When the difference between the charging state (SOC) of the current integration method and the charging state (SOC) of the voltage modeling method exceeds the predetermined error range in the error range comparison step, the charging state of the current integration method and the charging state of the voltage modeling technique A final charging state (SOC) calculating step of calculating a final charging state (SOC) by applying a predetermined weight;
Energy storage device (ESS) charging state (SOC) estimation method characterized in that comprises a. The method according to claim 1,
The state of charge (SOC) estimation step,
A current charging state (SOC) estimation step of estimating a charging state (SOC) of the energy storage device by applying the current measured in the state measuring step to a current integration method; And
A voltage charging state (SOC) estimation step of estimating a charging state (SOC) of the energy storage device by applying the current, voltage and temperature measured in the state measuring step to a voltage modeling technique;
Energy storage device (ESS) charging state (SOC) estimation method characterized in that comprises a. The method according to claim 1,
The error range comparison step may include: an estimation number comparison step of comparing whether the current charging state (SOC) estimation step exceeds a predetermined estimation number; It is configured to further include,
The method for estimating the state of charge (SOC) of an energy storage device (ESS), wherein the step of calculating the final state of charge (SOC) is performed when the current state of charge (SOC) estimation exceeds a predetermined number of times. State measuring unit for measuring the current, voltage and temperature of the energy storage device (ESS);
A charging state (SOC) estimator for estimating a charging state (SOC) based on each method by applying the current, voltage and temperature measured by the state measuring unit to a current integration method and a voltage modeling technique;
An error range comparison unit for comparing whether a difference between a charging state (SOC) of the current integration method estimated by the charging state (SOC) estimation unit and a charging state (SOC) of the voltage modeling method exceeds a predetermined error range;
When the difference between the charging state of the current integration method and the charging state of the voltage modeling method exceeds a predetermined error range in the error range comparison unit, a predetermined weight is applied to the charging state of the current integration method and the charging state of the voltage modeling technique. A final charging state (SOC) calculating unit for calculating a final charging state (SOC); And
A memory for storing each state of charge (SOC) estimated by the state of charge (SOC) estimator;
Energy storage device (ESS) charging state (SOC) estimation device comprising a. The method according to claim 4,
The state of charge (SOC) estimation unit,
A current integrator for estimating a state of charge (SOC) of the energy storage device by applying the current measured by the state measuring unit to a current integrating method; And
A voltage modeling unit that estimates a state of charge (SOC) of an energy storage device by applying current, voltage, and temperature measured by the state measuring unit to a voltage modeling technique;
Energy storage device (ESS) charging state (SOC) estimation device comprising a. The method according to claim 5,
The voltage modeling unit,
A charge / discharge determination unit for determining whether it is in a charged or discharged state based on the current and voltage measured by the state measurement unit;
A parameter deriving unit deriving a charging state (SOC) parameter based on the state determined by the charging / discharging determining unit; And
A voltage charging state (SOC) estimator estimating a charging state (SOC) of the energy storage device ESS based on the charging state (SOC) parameter derived from the parameter derivation unit;
Energy storage device (ESS) charging state (SOC) estimation device comprising a. The method according to claim 6,
The parameter derivation unit,
An energy storage device (ESS) charging state characterized by deriving a charging state (SOC) parameter based on the temperature measured by the state measuring unit and the estimated charging state (SOC) in the previous estimation cycle stored in the memory. (SOC) estimation device. The method according to claim 5,
The error range comparison unit,
The estimated number of charges (SOC) performed by the current integration unit is a predetermined number of estimates.
A comparison unit for estimating the number of times to compare whether it exceeds; Energy storage device (ESS) charging state (SOC) estimation device further comprises a.

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