KR20140094486A - Apparatus and method for estimating battery state and battery pack using it - Google Patents

Abstract

A device for estimating condition of a secondary battery pack in the present invention includes: a sensing unit for measuring the voltage and current of a battery pack; a calculation unit for, when the measurement count of the voltage and current reaches N (N is a natural number equal to or greater than 2), deducting a voltage drop due to the average current value of the N measured current value from the average voltage value of the N measured voltage values and setting an initial OCV value; a temporary setting unit for setting the result of deducting a voltage drop due to the currently measured current value after the N times of measurement as a temporary OCV value of the current step; and an OCV generation unit for generating the weighted average value between the temporary OCV value of the current step and the OCV value of the previous step as the current OCV value which is an OCV value of the current step after the N times of measurement. The present invention enables practical battery condition data to be estimated and utilized by utilizing the current and previous history data of a battery (pack) organizationally and estimating an OCV in diverse ways according to the characteristic of condition data.

Description

[0001] The present invention relates to an apparatus and method for estimating the state of a secondary battery battery pack, and a battery pack using the same.

The present invention relates to an apparatus and a method for estimating and managing a state of a secondary battery (pack), and a battery pack including the same. More specifically, the present invention relates to an OCV (Open Circuit Voltage) And more particularly, to an apparatus and method for estimating, generating and managing a more effective OCV and a remaining capacity of a battery using the same, and a battery pack using the same.

Secondary batteries having high electrical properties such as high energy density and high ease of application according to the product group are widely used not only in portable devices but also in electric vehicles (EVs) or hybrid vehicles (HVs) driven by electric driving sources Has been applied.

Such a secondary battery is not only a primary advantage that the use of fossil fuel can be drastically reduced, but also produces no by-products resulting from the use of energy, and thus is attracting attention as a new energy source for enhancing environmental friendliness and energy efficiency.

In recent years, the issue of depletion of energy resources by fossil fuels, issues of environmental pollution, and economical efficiency of energy use have been highlighted. Thus, it is necessary to effectively overcome the inconsistency between power consumption and power production, A smart grid system that flexibly adjusts the power supply amount in connection with various information communication infrastructures in order to solve overload caused by waste and power supply shortage is actively researched and the secondary battery is effective in such a smart grid system Energy storage and utilization.

The secondary battery may not necessarily be realized by a battery of a portable terminal or the like. However, as described above, a battery applied to an electric vehicle, an energy storage source, or the like is generally used in a form in which a plurality of unit secondary battery cells are collected And thus the suitability for a high-capacity environment is enhanced.

As shown in FIG. 1, when the battery module 10, in which a plurality of secondary battery cells 1 are assembled, is applied to an electric vehicle or the like, electric power control such as electric power supply control, current, A battery management system (BMS) for monitoring and controlling the state of a secondary battery is implemented by applying an algorithm for estimating a characteristic value, a charge / discharge control, a voltage equalization control, a state of charge (SOC) Device 30, and the like.

The battery management device 30 controls the electronic control device 31 and the like to control a power system supplied to the vehicle system 20 including a driving load such as a motor as described above, 10 to the vehicle system 20 so as to interfere with the current status of the battery or the like to the user or the driver.

As described above, the battery module 10, which is applied to a vehicle or the like, is composed of a plurality of secondary battery cells connected in series and / or parallel structure. Can be regarded as one system system by electrical connection of the plurality of secondary cells.

As is well known in the technical field to which the present invention belongs, unlike the gasoline engine system, the power system by the secondary battery can not generate state information about the power available at present and physically based on an absolute criterion, Various techniques for estimating or predicting the state of charge (SOC) using property values, variable information (voltage, current, accumulated current, temperature information, etc.) have been applied.

Such an estimation methodology can be classified into various types, and can be generally classified into an estimation method based on a parameter of a voltage such as an OCV and an estimation method based on a parameter of a current or an integrated current.

On the other hand, a battery mounted on an electric vehicle or the like is charged or discharged based on the electrochemical characteristics. When the driving of the vehicle is continued, the SOC is reduced by discharging. In such an environment, (Discharging) is continued, the battery enters a fully discharged state, and there is no additional power source in the electric vehicle, thereby causing a problem that the operation of the electric vehicle is interrupted.

In this case, the primary problem that the vehicle is no longer driven in an unintended state occurs, and at the same time, when the lithium ion secondary battery cell is exposed in the overdischarge state to the completely discharged state or the low voltage state thereof, The deterioration phenomenon of the electrochemical characteristics occurs, and if the battery is exposed to such an environment continuously, the deterioration phenomenon is accelerated to degrade the overall performance of the battery, and the life of the battery can not be guaranteed.

That is, it is necessary to estimate the remaining capacity of the battery accurately in order to interfere with accurate information about the available power to the vehicle operator and effectively maintain the performance of the battery.

In this regard, it is known that the battery estimation technique using the OCV described above has a merit that it can be implemented with a rather simple algorithm and hardware realizing it. However, the OCV value of the battery is a case where current flows by charging or discharging It has a problem that the reliability of its own value is not high because it has a profile characteristic to be stabilized after a certain period of time. Also, since an intelligent current may flow in the battery system or an inrush current may be generated, A considerable error may occur.

In addition, due to the inherent electrical and physical characteristics of the battery, although the current state of the battery is related to the previous characteristic profile, conventionally, only the method of generating or estimating the OCV based on the current state is applied, Therefore, it can be said that the reliability of the battery remaining capacity estimated by using the OCV can also be lowered.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems and needs in the background as described above, and it is an object of the present invention to estimate OCV with a more accurate and reliable OCV by a multi- And a method and a battery pack for estimating a state of a secondary battery battery pack that can be utilized for a remaining capacity or the like.

Other objects and advantages of the present invention will be described hereinafter and will be understood by the embodiments of the present invention. Further, the objects and advantages of the present invention can be realized by a combination of the constitution and the constitution shown in the claims.

According to an aspect of the present invention, there is provided an apparatus for estimating a state of a secondary battery battery pack, including: a sensing unit for measuring voltage and current of a battery pack; When the number of times of measurement of the voltage and the current is N (N is a natural number equal to or larger than 2), the voltage drop value by the average current value of each current value measured N times is subtracted from the average voltage value of each voltage value measured N times An operation unit for setting an initial OCV value; And setting a result of subtracting the voltage drop value by the current measurement current value from the current measured voltage value after the N times of measurement to the provisional OCV value of the current step; And an OCV generating unit for generating a weighted average value of the temporary OCV value of the current step and the OCV value of the previous step as a current OCV value which is an OCV value of the current step after the N times of measurement.

It is preferable that the present invention further includes an estimation unit that estimates a current remaining capacity of the battery pack using the current OCV value input from the OCV generation unit.

In addition, the present invention calculates the difference between the measured current value and the previous measured current value each time the current is measured. The M-1 current values and the mean The OCV generator of the present invention may further include a current value calculation unit for calculating a current value using a difference between the temporary OCV value of the current stage and the OCV value of the previous stage only when the average current variation is smaller than the reference current value. To the current OCV value.

The present invention further includes a determination unit for determining whether the temporary OCV value of the present stage set by the threshold management unit falls within a reference voltage variation value range when the average current variation is larger than the reference current variation In this case, the OCV generator of the present invention is configured to generate the temporary OCV value of the current stage as the current OCV value when the temporary OCV value of the current stage falls within the reference voltage variation value range.

Further, the OCV generator of the present invention generates an upper limit value of the reference voltage variation value range as the current OCV value when the temporary OCV value of the current stage exceeds the upper limit value of the reference voltage variation value range, And generates a lower limit value of the reference voltage variation value range as the current OCV value when the temporary OCV value does not reach the lower limit value range of the reference voltage variation value range.

According to another aspect of the present invention, there is provided a method of estimating a state of a rechargeable battery pack, comprising: sensing a voltage and a current of a battery pack; When the number of times of measurement of the voltage and the current is N (N is a natural number equal to or larger than 2), the voltage drop value by the average current value of each current value measured N times is subtracted from the average voltage value of each voltage value measured N times An operation step of setting an initial OCV value; A temporary setting step of setting a result of subtracting the voltage drop value by the current measurement current value from the current measured voltage value after the Nth measurement to the temporary OCV value of the current step; And an OCV generation step of generating a weighted average value of the temporary OCV value of the current stage and the OCV value of the previous stage as a current OCV value which is an OCV value of the current stage after the N times of measurement.

According to another aspect of the present invention, there is provided a secondary battery pack comprising: a battery module including a plurality of secondary batteries; a sensing unit for measuring voltage and current of the battery module; (N is a natural number equal to or greater than 2), the voltage drop due to the average current value of each current value measured for the N times is subtracted from the average voltage value of each of the N measured voltage values, And a controller for setting a result of subtracting the voltage drop value based on the current measurement current value from the current measured voltage value after the Nth measurement to the temporary OCV value of the current stage, and a temporary OCV value And an OCV generating unit for generating a weighted average value of the OCV values of the previous step as a current OCV value that is an OCV value of the current step after the N times of measurement .

The apparatus and method for estimating the state of a secondary battery (pack) according to the present invention and the battery pack using the same are capable of avoiding a method of merely reflecting the current state and organically utilizing current and past history information of the battery pack, It is possible to estimate the OCV using a diversified method according to the characteristics of the battery, and to provide more effective battery state information.

In addition, the algorithms for estimating and generating the OCV are diversified and applied differentially to improve the accuracy and reliability of the remaining capacity information such as the OCV information and the SOC using the OCV information. In addition, surge current inflow or sudden large charge / discharge Even if the battery exhibits an unusual state, it can be robustly coped with by filtering using a statistical functional relationship, and moreover it is possible to provide more practical SOC information about the battery to a user such as a driver, It is possible to provide an advantage that the operation can be implemented more stably and safely.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a schematic view showing a configuration of a general battery pack managing apparatus,
2 is a block diagram showing the configuration of a battery pack state estimating apparatus according to a preferred embodiment of the present invention.
3 is a flowchart illustrating a method of estimating a state of a battery pack according to an exemplary embodiment of the present invention.
4 is a block diagram showing the configuration of a battery pack according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

FIG. 2 is a block diagram showing a configuration of a battery pack state estimating apparatus (hereinafter referred to as an estimating apparatus) 100 according to a preferred embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of a battery pack according to a preferred embodiment of the present invention. FIG. 4 is a flowchart showing a process of a state estimation method of a pack. FIG.

2, the estimating apparatus 100 of the present invention includes a sensing unit 110, an arithmetic unit 120, a finishing unit 130, an OCV generating unit 140, an estimating unit 150, A controller 160, a determination unit 170, and a memory unit 180.

The sensing unit 110 includes a voltage sensor and a current sensor. The sensing unit 110 may include a temperature sensor for correcting a measured value according to an embodiment of the present invention. The sensing unit 110 measures a voltage and a current of the battery pack 10 according to a predetermined period (S300), and outputs the measured information or data to other components of the present invention to be described later.

As described above, the battery (pack) 10 corresponds to an assembly in which a plurality of secondary battery unit cells are connected in series or in parallel. The sensing unit 100 measures voltage and current for one battery pack 100 as a system and can utilize the voltage and current through the following configuration of the present invention. Of course, can be applied. Hereinafter, an object for measuring voltage and current will be described as an example of a battery pack.

As described above, the present invention estimates, generates, and utilizes accurate and reliable OCV, and estimates the OCV and the remaining capacity (SOC, etc.) of the battery using the OCV so as to correspond to driving continuity of the electric vehicle or the hybrid electric vehicle It can be seen that the clock is made thermally.

The present invention proposes a methodology for estimating and generating an OCV of a current time point by statistically linking history information or data up to a current time point rather than simply estimating an OCV based on only the current time point.

First, the initial OCV of the battery pack, which can be a reference, is set. When the voltage and current of the battery pack are measured N times, which is determined as the reference number of times in the sensing unit 110 (S310) The controller 120 calculates an average voltage value of each of the N measured voltage values by using the measured N voltage values and current values, The initial OCV value is set by subtracting the voltage drop value (S320).

In Equation (1), N is a natural number of 2 or more, V _n is a measured voltage each time, I _n is a measured current each time, and R is a resistance value of the battery pack. In the present invention, the voltage and current of the battery pack are measured by the reference number of times (N) prior to full-scale OCV estimation at the time point, and the initial OCV is set by the measured value and the calculation of Equation (1). Since the methodology of the present invention utilizes the past history data as described later, the methodology of the present invention requires past data based on the current time point, so that the initial OCV becomes a value serving as a reference of past history data.

In this way, the initial OCV to be a reference is set prior to the full OCV estimation, and based on the initial OCV, the OCV is used as an initial reference for the historical data for estimating the OCV at the present stage or the present time.

It is needless to say that the reference number N can be variously set in consideration of the system environment, hardware resources, data processing capabilities, battery specifications, characteristics of applied devices, and the like.

If the initial OCV is set as described above, the OCV is estimated at a current present time (present stage). For this purpose, the provisional monitoring unit 130 of the present invention first calculates the OCV at the current time The result of subtracting the voltage drop due to the current measurement current value to the voltage value is set as the temporary OCV value of the current stage (S330).

In Equation 2 OCV _{temp _t} means the temporary OCV at the current time and, V _t refers to the voltage value measured at the current point in time (phase) and, I _t will correspond to the current value measured at the present time (step) And R corresponds to the resistance value of the battery pack. Also, t is a variable that is periodically increased as a measurement point or a recurrence, and as described above, when the absolute time point is used as a reference, the point-in-time t is the point in time after the measurement of N times.

In a conventional method of simply using the voltage value measured at the present time point as the OCV and estimating the remaining capacity or the like of the battery pack at the present time using the OCV, history information on the characteristics of the battery pack previously performed is not taken into consideration at all The present invention is not limited thereto.

In order to solve this problem, the OCV generator 140 of the present invention determines the degree of voltage drop based on the current value measured according to Equation (2) So that the measured voltage value is not used as it is.

At the same time, the calculated result is set as a potential temporary value without using the result as it is, and a temporary average OCV value of the current stage and an OCV value determined in the previous stage are calculated according to Equation (3) (Step S360) as the current step OCV value after the Nth measurement.

Through such processing, it is possible to effectively reflect the time-dependent characteristics of the battery so that the characteristic information on the battery pack in the previous step can be utilized continuously, thereby further increasing the reliability of the OCV value.

The formula in the OCV is _t OCV, OCV _{_t temp} is a temporary OCV, the OCV _{t -1} at the present time from the current time point is prior to step OCV determined in the previous step, the last stage based on the current point in time, F is 0 and 1, Is a variable for weight calculation.

The variable F is a value that can be variously set based on the life of the battery, the resolution and accuracy of the measurement sensor, and the reliability of the current battery system. The larger the value of F, the higher the reliability of the measured value. The smaller the value, the higher the degree of reflection on the past history data value.

When the current OCV of the battery pack is generated by the above method, the estimator 150 of the present invention receives the current OCV value from the OCV generator 140, (S385). ≪ / RTI >

Various methods known to those skilled in the art can be applied to the method of estimating the remaining capacity such as the SOC of the battery pack 10 by using the OCV value, and thus a detailed description thereof will be omitted.

On the other hand, it is known that the current sensor rather than the voltage sensor has a relatively large influence due to external factors and has a considerable error range due to high sensitivity of sensing. Therefore, it is more preferable to reflect such a situation so that the measured current value can be more accurately reflected.

In order to effectively reflect this, the current variation arithmetic unit 160 of the present invention calculates the difference between the current measured value and the previously measured current value each time the current of the battery pack 10 is measured, that is, (M is a natural number equal to or greater than 2) current values based on the present stage, and calculates M-1 current variances. When M-1 current variances are calculated, the average current variance is calculated (S340).

That is, a statistical average value of the past M-1 current variations is calculated on the basis of the present time as a reference as shown in Equation (4) below.

In Equation (4), M is a variable corresponding to a numerical range for calculating an average current variance, and may be determined by reflecting various factors and circumstances such as the reference number N described above, and N and M may be set to the same number Of course it is. Here, N denotes the number of statistical entities for determining the initial OCV, and M denotes a statistical entity for previous data referenced in the past based on the current point of view in relation to the full OCV determination after the initial OCV determination N and M are independent variables meaning and conceptually.

As described above, when the average current variance for the recent M-1 current measurement values is calculated in the present time base inverse time direction, it is determined how the magnitude of the average current variation is different from the reference current variation.

As described above, the measured current values are significantly affected by the external environment such as the error of the current sensing sensor, the inrush current, and the surge current, so that the average current variation in the current state can be detected in the battery pack It is necessary to evaluate whether or not the average current variation in the current state is affected by the external environment in comparison with the average current variation based on the battery pack system.

Particularly, the fact that the average current variation in the current state is smaller than the reference current variation means that the variation range of the current is small, so that the current flow in the battery can be regarded as not being within the error range, It is also possible to say that it maintains. In such a case, the electrical characteristic value such as the OCV of the battery may have a considerably large correlation with the previous characteristic information.

In order to effectively reflect such electrophysical characteristics, the OCV generator 140 of the present invention compares the average current variation with the reference current variation as described above (S350), and only when the average current variation is smaller than the reference current variation, (Step S360) so as to generate the current OCV value as a weighted average value of the temporary OCV value of the previous step and the OCV value of the previous step.

On the other hand, the current average value of the current is larger than the reference current, which means that the current flow in the battery is changed to a significant extent. That is, it can be considered that the battery is in a discharged state and therefore the vehicle is being driven at a speed higher than the reference acceleration, or the battery is in a charged state, so that a change in the battery OCV or the like is largely occurring.

That is, since the battery is in an environment such as driving the vehicle or charging the battery, the characteristics of the current state itself are more important than the correlation or relevance of the past hysteresis characteristics. In such a case, it is preferable to configure the current OCV to be the temporary OCV value of the current stage (S380) because reliability can be further given to the temporary OCV value itself calculated by Equation (2).

However, if the OCV value itself is too large or too small, it may be regarded as an unusual situation due to an external factor rather than an influence of actual battery operation, so that the temporary OCV value is a normal value range that can be achieved in a normal battery condition It is more preferable to compare the temporary OCV value with a reference value for determining the current OCV value so that the current OCV is discriminated according to the result.

For this, when the average current variation is greater than the reference current variation, the determination unit 170 determines that the provisional OCV value of the present stage set in the finishing facility 130 is within the reference voltage variation value range The OCV generator 140 of the present invention determines whether the temporary OCV value of the current stage falls within the reference voltage variation value range, OCV value (S380).

In the above formula V _min is the lower limit of the range of the reference voltage change value, V _max corresponds to a variable which can be determined by experiments and statistical methods as the upper limit of the range of the reference voltage change value.

If determined that the temporary OCV value is based on the case that is outside the voltage change range of values are greater than the upper limit (V _max) (S373), it is difficult to ensure the reliability of the temporary OCV value itself present in the determining section 170 The OCV generator 140 of the present invention generates the upper limit value of the reference voltage change value range as the current OCV value at step S375. That is, the OCV value calculated at the present stage is relied on, but reliability is given in a limited range up to the upper limit of the reference voltage variation value.

If the temporary OCV value is out of the range of the reference voltage variation value and does not reach the lower limit, the OCV generator 140 of the present invention, in view of the above, corresponds to the lower limit value of the reference voltage variation range V _min ) is generated as the current OCV value (S377).

It is a matter of course that various information including the current OCV described above can be stored and utilized in the memory unit 180 of the present invention.

As described above, according to the present invention, the current OCV information of the battery is applied in a different or multiple manner depending on the current state of the battery by organically utilizing the data measured at the current stage and the historical data measured in the past so as to generate more reliable OCV information .

4, the estimating apparatus 100 may be implemented as a system of the battery pack 200 itself shown in FIG. 4 or the like. As shown in FIG. 4, the estimating apparatus 100 according to another aspect of the present invention includes a battery pack 200 May be configured to include a battery module 210 serving as a source of charging and discharging and supplying power to a vehicle or the like and an estimation module 220 implemented as a module as described above, (220) may be implemented as a BMS or the like.

The battery module 210 may include a plurality of secondary batteries 211. The estimation module 220 of the battery pack 200 according to the present invention may include an OCV, Information on remaining capacity of the battery, etc., to the vehicle system 300, or input necessary information from a user or the like.

The detailed description of the configuration including the estimation module 220 of the battery pack 200 is the same as that of the estimation device 100 described above,

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 to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

In addition, each configuration of the estimating apparatus 100 of the present invention shown in FIG. 2 and the like should be understood as a component that is logically divided or a component including the component, rather than being a physically separated component.

That is, since each constitution corresponds to a logical constituent element for realizing the technical idea of the present invention, even if each constituent element is integrally or separately performed, if the function performed by the logical constitution of the present invention can be realized, It is to be understood that any component that performs the same or similar function should be interpreted as falling within the scope of the present invention regardless of the consistency of the name.

1: secondary battery cell 10: battery (pack)
100: Estimation device 110:
120: operation unit 130:
140: OCV generation unit 150:
160: current variation arithmetic operation unit 170:
180:

Claims (6)

A sensing unit for measuring voltage and current of the battery pack;
When the number of times of measurement of the voltage and the current is N (N is a natural number equal to or larger than 2), the voltage drop value by the average current value of each current value measured N times is subtracted from the average voltage value of each voltage value measured N times An operation unit for setting an initial OCV value;
And setting a result of subtracting the voltage drop value by the current measurement current value from the current measured voltage value after the N times of measurement to the provisional OCV value of the current step; And
And an OCV generating unit for generating a weighted average value of the temporary OCV value of the current stage and the OCV value of the previous stage as a current OCV value that is an OCV value of the current stage after the N times of measurement, . The method according to claim 1,
Further comprising an estimator for estimating a current remaining capacity of the battery pack using the current OCV value input from the OCV generator. A sensing step of measuring voltage and current of the battery pack;
When the number of times of measurement of the voltage and the current is N (N is a natural number equal to or larger than 2), the voltage drop value by the average current value of each current value measured N times is subtracted from the average voltage value of each voltage value measured N times An operation step of setting an initial OCV value;
A temporary setting step of setting a result of subtracting the voltage drop value by the current measurement current value from the current measured voltage value after the Nth measurement to the temporary OCV value of the current step; And
An OCV generation step of generating a current average OCV value of the current stage and a weighted average value of the OCV value of the previous stage as a current OCV value of the current stage after the N times of measurement; Way. The method of claim 3,
And estimating a current remaining capacity of the battery pack using the current OCV value of the OCV generation step. A battery module comprising a plurality of secondary batteries:
A sensing part for measuring a voltage and a current of the battery module, and a control part for comparing the average voltage value of each of the N measured voltage values with the measured voltage value for the N times (N is a natural number of 2 or more) A subtracter for subtracting the voltage drop value by the current value of the current value, and setting an initial OCV value by subtracting the voltage drop value by the average current value of each current value; And an OCV generating unit for generating a weighted average value of the provisional OCV value of the current stage and the OCV value of the previous stage as the current OCV value that is the OCV value of the current stage after the N times of measurement, Wherein the battery pack is a battery pack. 6. The apparatus of claim 5,
Further comprising an estimating unit estimating a current remaining capacity of the battery module using the current OCV value input from the OCV generating unit.

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