KR101783918B1 - Apparatus and Method for Estimating Resistance of Secondary Battery - Google Patents

Abstract

The present invention discloses an apparatus and method for estimating resistance of a secondary battery. The apparatus for estimating resistance of a secondary battery according to the present invention includes a memory unit storing a plurality of resistance lookup information that can map a resistance corresponding to a charged state and a temperature of a secondary battery for each resistance increase rate of the secondary battery; Determining a reference resistance of the secondary battery when the charged state and temperature of the secondary battery correspond to the reference SOC and the reference temperature, determining a resistance increase rate of the reference resistor based on the BOL resistance of the secondary battery, And a controller that identifies corresponding resistance lookup information in the memory unit and estimates a resistance of the secondary battery corresponding to a certain charging state and temperature using the identified resistance lookup information.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating the resistance of a secondary battery,

The present invention relates to an apparatus and a method for estimating a resistance, which is one of the factors indicating the state of health of a secondary battery.

BACKGROUND ART [0002] In recent years, secondary batteries capable of repeated charging and discharging have attracted attention as an alternative means of fossil energy.

Secondary cells have been used predominantly in traditional handheld devices such as cell phones, video cameras, and power tools. In recent years, however, application fields of electric vehicles (EV, HEV, PHEV), large capacity electric power storage (ESS) and uninterruptible power supply system (UPS) have been gradually increasing.

The secondary battery includes a positive electrode and a negative electrode, a separator interposed between the electrodes, and an electrolyte electrochemically reacting with the active material coated on the positive electrode and the negative electrode.

The capacity of the secondary battery decreases as the number of charge / discharge increases. The reduction of the capacity can be attributed to deterioration of the active material coated on the electrode, negative reaction of the electrolyte, reduction of the pore of the separation membrane, and the like.

When the capacity of the secondary battery decreases, the resistance increases and the electric energy lost by heat increases. Therefore, if the capacity of the secondary battery is reduced below the threshold value, the performance of the secondary battery is remarkably deteriorated and the amount of generated heat is increased, so that it needs to be checked or replaced.

In the field of secondary battery technology, the degree of capacity reduction of a secondary battery can be quantitatively represented by a factor called a state of health (SOH).

SOH can be calculated in various ways, one of which can be calculated by quantifying the degree of increase in resistance relative to the resistance when the resistance of the secondary cell is in the BOL (Beginning Of Life) state .

For example, if the resistance of the secondary battery is increased by 20% with respect to the resistance when it is in the BOL state, SOH can be estimated to be 80%.

The resistance of the secondary battery tends to be relatively large when the state of charge (SOC) is low and relatively small when the temperature is high.

When the charged state of the secondary battery is lowered, the amount of the active material capable of reacting with the working ion decreases, and the diffusion resistance of the working ion increases in the active material and the mobility of the working ion increases as the temperature of the secondary battery increases to be.

For reference, the working ion differs depending on the kind of the chemical constituting the secondary battery. In the case of the lithium-based battery, the lithium ion corresponds to the working ion.

The resistance of the secondary battery is a necessary parameter for calculating the charging output and the discharging output of the secondary battery. However, during the charging or discharging of the secondary battery, it is difficult to accurately measure the resistance of the secondary battery due to polarization of the active material. Therefore, conventionally, a method of indirectly estimating the resistance of the secondary battery by using the current, voltage, and temperature of the secondary battery has been mainly used.

One of the simple resistance estimation methods of calculation algorithms is Direct Current Resistance Estimation. In the DC estimation method, a voltage change amount is measured under a condition that a secondary cell is charged or discharged by a constant current, a resistance is calculated by Ohm's law (R = DELTA V / I) As shown in FIG.

However, during the charging or discharging of the secondary battery, it is difficult to accurately measure the voltage change due to polarization of the active material. Therefore, the resistance calculated by the DC estimation method is less accurate depending on the degree of polarization of the active material.

For example, if the polarity of the active material is different even if the charged state and the temperature are the same, the DC estimation method gives different calculation results for the resistance of the secondary battery.

On the other hand, a method of estimating the resistance of a secondary battery using an adaptive algorithm such as an extended Kalman filter is widely used to overcome the problem of the DC estimation method.

However, adaptive algorithms require a high-performance processor with high computational complexity and stability. Therefore, the application of the adaptive algorithm has a problem of increasing the manufacturing cost of the battery management system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and a method for estimating a resistance of a secondary battery with a simple algorithm, which is developed under the background of the prior art as described above.

According to an aspect of the present invention, there is provided an apparatus for estimating a resistance of a secondary battery, the apparatus comprising: a plurality of resistive lookup tables for mapping a resistance corresponding to a charging state and a temperature of the secondary battery, A memory unit for storing the image data; Determining a reference resistance of the secondary battery when the charged state and temperature of the secondary battery correspond to the reference SOC and the reference temperature, determining a resistance increase rate of the reference resistor based on the BOL resistance of the secondary battery, And a controller that identifies corresponding resistance lookup information in the memory unit and estimates a resistance of the secondary battery corresponding to a certain charging state and temperature using the identified resistance lookup information.

Preferably, the reference SOC is 40-60%, and the reference temperature may be 20-30 < 0 > C.

Preferably, the apparatus for estimating the resistance of the secondary battery further includes: a voltage measuring unit for measuring a voltage of the secondary battery; A current measuring unit for measuring a current of the secondary battery; And a temperature measuring unit for measuring a temperature of the secondary battery. The controller may be configured to store the voltage measurement value, the current measurement value, and the temperature measurement value in the memory unit.

According to an aspect of the present invention, the controller may be configured to determine a state of charge of the secondary battery by integrating a current measurement value stored in the memory unit.

Preferably, the control unit identifies a measured value of a current charged or discharged at the reference SOC and the reference temperature among the voltage measurement value and the current measurement value stored in the memory unit, Identify two voltage measurements, and determine a reference resistance from the amount of change in the voltage measurement and the current measurement.

Preferably, the resistance lookup information may be a resistance lookup table having a data structure capable of mapping the resistance of the secondary battery according to a charged state and a temperature of the secondary battery.

According to another aspect, the control unit may be configured to store the estimated resistance in the memory unit, determine an output of the secondary battery using the estimated resistance, or transmit the estimated resistance to an external device .

According to another aspect of the present invention, there is provided an apparatus for estimating a resistance of a secondary battery, the apparatus comprising: a plurality of resistors for mapping a resistance corresponding to a charging state and a temperature of the secondary battery, A memory unit storing the resistance lookup information of the memory; And

The reference resistance of the secondary battery is determined when the charged state and temperature of the secondary battery correspond to the reference SOC and the reference temperature and the comparison resistance of the secondary battery is determined when the charging state and the temperature of the secondary battery correspond to the reference SOC and the comparison temperature Determining a BOL resistance of the secondary battery and a resistance increase rate from the reference resistance, determining a degradation acceleration index from a ratio of the reference resistance and the comparison resistance, and comparing the resistance increase rate and the resistance lookup information And estimating a resistance of the secondary battery corresponding to an arbitrary state of charge and temperature from the identified resistance lookup information.

Preferably, the reference SOC is 40-60%, the reference temperature is 20-30 ° C, and the comparison temperature is -10-10 ° C.

Preferably, the apparatus for estimating the resistance of the secondary battery further includes: a voltage measuring unit for measuring a voltage of the secondary battery; A current measuring unit for measuring a current of the secondary battery; And a temperature measuring unit for measuring a temperature of the secondary battery. The controller may be configured to store the voltage measurement value, the current measurement value, and the temperature measurement value in the memory unit.

Preferably, the control unit identifies a measured value of a current charged or discharged at the reference SOC and the reference temperature among the voltage measurement value and the current measurement value stored in the memory unit, Identify two voltage measurements, and determine a reference resistance from the amount of change in the voltage measurement and the current measurement.

Similarly, the control unit may identify the reference SOC and a measured value of the current charged or discharged at the comparison temperature among the voltage measurement value and the current measurement value stored in the memory unit, Identify two voltage measurements, and determine the comparison resistance from the amount of change in the voltage measurement and the current measurement.

According to an aspect of the present invention, there is provided a method of estimating a resistance of a secondary battery, the method comprising the steps of: (a) Storing the resistance lookup information in a memory unit; (b) receiving a voltage measurement value, a current measurement value, and a temperature measurement value from the voltage measurement unit, the current measurement unit, and the temperature measurement unit, and storing the received voltage measurement value, current measurement value, and temperature measurement value in the memory unit; (c) determining a state of charge of the secondary battery using the current measurement value and storing the state of charge in the memory unit; (d) measuring a current value of the charged or discharged current when the charging state and the temperature of the secondary battery correspond to the reference SOC and the reference temperature among the current measurement value and the voltage measurement value stored in the memory unit, Determining a reference resistance of the secondary battery using the change amount of the voltage measurement value and the current measurement value; (e) determining a resistance increase rate of the reference resistor based on a BOL resistance of a predetermined secondary battery; (f) identifying in the memory unit resistance lookup information corresponding to the resistance increase rate; And (g) estimating a resistance of the secondary battery corresponding to an arbitrary state of charge and temperature using the identified resistance lookup information.

According to another aspect of the present invention, there is provided a method of estimating a resistance of a secondary battery, comprising the steps of: (a) mapping a resistance corresponding to a charging state and a temperature of the secondary battery according to a resistance increase rate and a degradation acceleration index of the secondary battery; Storing a plurality of resistive lookup information in a memory unit; (b) receiving a voltage measurement value, a current measurement value, and a temperature measurement value from the voltage measurement unit, the current measurement unit, and the temperature measurement unit, and storing the received voltage measurement value, current measurement value, and temperature measurement value in the memory unit; (c) determining a state of charge of the secondary battery using the current measurement value and storing the state of charge in the memory unit; (d) determining a reference resistance and a comparison resistance of the secondary battery by identifying a voltage measurement value and a current measurement value measured at a reference temperature and a comparison temperature when the state of charge of the secondary battery is the reference SOC, from the memory; (e) determining a BOL resistance of the secondary battery and a resistance increase rate from the reference resistance; (f) determining a degradation acceleration index from a relative ratio of the reference resistance and the comparison resistance; (g) identifying in the memory unit resistance lookup information corresponding to the determined resistance increase rate and the degradation acceleration index; And (h) estimating a resistance of the secondary battery corresponding to an arbitrary state of charge and temperature using the identified resistance lookup information.

The present invention also provides a secondary battery management system including a resistance estimating device for a secondary battery, and a computer readable recording medium storing a program for estimating a resistance of the secondary battery.

According to an aspect of the present invention, the resistance increase rate of the secondary battery can be changed based on the BOL resistance in the charging state period in which the resistance change of the secondary battery is small, thereby changing the resistance lookup information (table) used for estimating the resistance of the secondary battery. Therefore, it is possible to reliably estimate the resistance of the secondary battery in accordance with the degradation state of the secondary battery in a relatively simple manner.

According to another aspect of the present invention, by further considering the degradation acceleration index when changing the resistance lookup information (table) used for estimating the resistance of the secondary battery, the charging / discharging environment of the secondary battery is taken into consideration, The resistance of the secondary battery can be reliably estimated.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and, together with the description given below, serve to further augment the technical spirit of the invention, And shall not be interpreted.
FIG. 1 is a block diagram schematically illustrating a configuration of a resistance estimating apparatus for a secondary battery according to an embodiment of the present invention. Referring to FIG.
2 is a diagram illustrating a plurality of resistance lookup tables stored in a memory unit when the resistance lookup information according to the present invention is configured in the form of a lookup table.
FIG. 3 is a graph illustrating resistance of a secondary battery having different degradation conditions according to an embodiment of the present invention, measured according to charging states.
4 is a diagram illustrating a plurality of resistance lookup tables stored in the memory when the degradation acceleration index is considered in the resistance estimation process according to the present invention.
5 is a flowchart sequentially illustrating a method of estimating a resistance of a secondary battery according to an embodiment of the present invention.
6 is a flowchart sequentially illustrating a method of estimating a resistance of a secondary battery according to a modified example of the present invention.

Hereinafter, embodiments of the present invention will be described 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 meanings, and the inventor should appropriately interpret the concept of a term appropriately in order to describe its own application in the best way possible. 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 the present specification and the configurations shown in the drawings are only examples of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents And variations are possible.

In the embodiments described below, the secondary battery refers to a lithium secondary battery. Here, the lithium secondary battery is generally referred to as a secondary battery in which lithium ions act as working ions during charging and discharging to cause an electrochemical reaction between the positive electrode and the negative electrode.

On the other hand, even if the name of the secondary battery is changed depending on the kind of the electrolyte or separator used in the lithium secondary battery, the kind of the packing material used for packing the secondary battery, internal or external structure of the lithium secondary battery, The secondary battery should be interpreted as being included in the category of the lithium secondary battery.

The present invention is also applicable to secondary batteries other than lithium secondary batteries. Therefore, even if the working ion is not lithium ion, any kind of secondary battery to which the technical idea of the present invention can be applied should be interpreted as falling within the scope of the present invention.

The secondary battery is not limited by the number of elements constituting it. Thus, the secondary battery may be a single cell assembly including a single cell containing a cathode / separator / cathode assembly and an electrolyte in one package, a module in which a plurality of assemblies are connected in series and / or in parallel, a plurality of modules connected in series and / A pack connected in parallel, a battery system in which a plurality of packs are connected in series and / or in parallel, and the like.

1 is a block diagram illustrating a configuration of a resistance estimating apparatus for a secondary battery according to an embodiment of the present invention.

Referring to FIG. 1, an apparatus for estimating resistance of a secondary battery according to the present invention includes at least a memory unit 110 and a control unit 120 as an apparatus for estimating a resistance of a secondary battery.

The controller 120 includes a processor capable of performing a logic operation and performs a function of estimating a resistance corresponding to a charged state and a temperature of the secondary battery B according to a control logic to be described later.

 The memory unit 110 is a storage medium capable of recording and erasing data electrically, magnetically, optically or quantum mechanically.

The memory unit 110 may be, for example, a RAM, a ROM, or a register as a non-limiting example.

The memory unit 110 may be connected to the controller 120 through a data bus or the like so that the memory unit 110 can be accessed by the controller 120.

The memory unit 110 may store and / or update and / or update the program including the various control logic executed by the control unit 120 and the predefined parameters, and / or data generated when the control logic is executed, Or erase it.

The memory unit 110 may be logically divided into two or more, and is not limited to being included in the control unit 120.

Preferably, the memory unit 110 stores a plurality of resistance lookup information that can map the resistance of the secondary battery B corresponding to the charged state (SOC) and the temperature of the secondary battery B by the magnitude of the resistance increase rate It is stored in advance.

Preferably, the plurality of resistive lookup information may include a plurality of resistive lookup tables defined according to the magnitude of the rate of resistance increase, as shown in FIG.

Each of the resistance look-up tables includes a data structure capable of mapping resistances by charge state and temperature. The data constituting the resistance lookup table shows how the resistance of the secondary battery B changes according to the charging state and the temperature of the secondary battery when the secondary battery B has a specific resistance increase rate based on the BOL resistance. The resistance data constituting each resistance lookup table can be measured in advance through the charge / discharge test for the secondary battery B having different resistance increasing rates.

The controller 120 may be electrically coupled to the voltage measuring unit 130, the current measuring unit 140, and the temperature measuring unit 150 to determine the charging state and the resistance of the secondary battery B .

The voltage measuring unit 130 includes a known voltage measuring circuit and periodically measures the voltage of the secondary battery B with a time interval under the control of the controller 120 and outputs the measured voltage value to the controller 120. [ . Then, the control unit 120 stores the voltage measurement value periodically input to the memory unit 110. FIG.

The current measuring unit 140 includes a sense resistor and a hall sensor and measures a magnitude of a charging current or a discharging current of the secondary battery B with a time interval under the control of the controller 120, (120). Then, the control unit 120 stores the current measurement value periodically input to the memory unit 110. FIG.

The temperature measuring unit 150 includes a thermocouple as a kind of temperature sensor and periodically measures the temperature of the secondary battery B with a time interval under the control of the controller 120 to measure the temperature of the secondary battery B, . Then, the control unit 120 stores the temperature measurement value periodically input to the memory unit 110. FIG.

The control unit 120 may determine the state of charge of the secondary battery periodically by the current integration method referring to the current measurement value stored in the memory unit 110. [

Specifically, when the charging or discharging of the secondary battery B is started, the control unit 120 controls the voltage measuring unit 130 to measure the open circuit voltage (OCV) of the secondary battery B , Determines an initial charge state (SOC ₀ ) corresponding to the measured open-circuit voltage with reference to the 'OCV-SOC lookup table' stored in advance in the memory unit 110, The present charging state can be determined by adding the accumulated value of the discharging current to the initial charging state (SOC ₀ ), and the determined charging state can be stored in the memory unit 110.

Of course, the state of charge of the secondary battery B can also be determined by a method other than the current integration method. For example, the control unit 120 may periodically input a voltage measurement value, a current measurement value, and a temperature measurement value into an adaptive filter, for example, an extended Kalman filter to adaptively determine the state of charge of the secondary battery.

An example of a charging state determination technique using the extended Kalman filter is disclosed in US Patent No. 7,589,532, entitled SYSTEM AND METHOD FOR ESTIMATING A STATE VECTOR ASSOCIATED WITH A BATTERY.

The control unit 120 monitors the latest state of charge state and temperature of the secondary battery B stored in the memory unit 110 and determines whether a condition corresponding to a reference SOC and a reference temperature, The reference resistance of the secondary battery B can be determined.

Specifically, the control unit 120 determines whether the current and / or the voltage of the secondary battery B is lower than the reference voltage SOC of the secondary battery B, And the voltage measurement value measured before and after the current flows, and by dividing the change amount of the voltage measurement value by the magnitude of the current measurement value by the Ohm's Law law, the reference resistance of the secondary battery (B) You can decide. In addition, the controller 120 may store the determined reference resistance in the memory unit 110.

In the present invention, the reference SOC is defined in advance, and can be arbitrarily selected in the SOC region in which the resistance change amount of the secondary battery is relatively small compared with the variation amount of the charging state.

For example, the reference SOC may be selected in the range of 40 to 80%. In addition, the reference temperature may be selected in the range of about 20 to 30 DEG C near room temperature at which the secondary battery B exhibits an average performance.

FIG. 3 is a graph showing how the resistance of a lithium secondary battery including LiMnO ₂ and graphite in an anode and a cathode, respectively, changes with charging state.

3, the solid line is the resistance profile measured when the lithium secondary battery is in the BOL state, and the dotted line is the resistance profile measured in the MOL (Middle Of Life) state in which the capacity of the lithium secondary battery is degraded by about 20%.

Each resistance profile was obtained by HPPC (Hybrid Pulse Power Characterization) discharge test. In the HPPC test, the discharge time was set to 10 seconds and the discharge pulse size was set to 5c-rate. During the HPPC test, Lt; RTI ID = 0.0 > 25 < / RTI >

As shown in FIG. 3, the resistance of the lithium secondary battery increases as the charging state decreases, and when the charging state falls within the range of 40 to 80%, it can be seen that the change in resistance is not relatively large. Therefore, the reference SOC can be selected in the range of 40 to 80% for the lithium secondary battery.

The controller 120 determines the resistance increase rate with respect to the reference resistance based on the BOL resistance (resistance in the BOL state) of the secondary battery B stored in the memory unit 110 It is possible to identify the resistance lookup table corresponding to the resistance increase rate determined from the plurality of resistance lookup tables stored in the memory unit 110 and to use the identified resistance lookup table as the resistance lookup table used for estimating the resistance of the secondary battery B It can be specified as a table.

The controller 120 may also estimate the resistance of the secondary battery B corresponding to an arbitrary charging state and temperature by referring to the designated resistance lookup table after the resistance lookup table is designated, (110).

In a preferred example, if the resistance lookup information is comprised of a plurality of resistive lookup tables as shown in FIG. 2, it identifies the resistive lookup table corresponding to the determined resistive increase rate, The resistance of the secondary battery B can be estimated by mapping the resistance of the secondary battery B corresponding to the temperature.

2, if the current charging state and the temperature of the secondary battery B are 60% and 20 ° C respectively when the resistance increase rate of the reference resistance is 30%, the resistance of the secondary battery B is 1.1 mΩ .

The controller 120 may also determine the output of the secondary battery B using the estimated resistance of the secondary battery B and store the determined output information in the memory unit 110. [

As an example, the output of the secondary battery B can be calculated using the following equation.

Output of secondary battery =

In the above equation, I represents the magnitude of the charging current or the discharging current of the secondary battery (B). OCV _@ SOC can be referred to from the 'OCV-SOC lookup table' stored in the memory unit 110 as an open-circuit voltage corresponding to the current state of charge of the secondary battery B. V _{cut_off} is a voltage at which the charging or discharging of the secondary battery is cut off. The maximum cut-off voltage V _max when the secondary battery B is charged and the minimum discharge voltage V _min when the secondary battery B is discharged . R _{@ SOC, T} represents the resistance corresponding to the present charging state and temperature of the secondary battery B, and is estimated by the present invention.

The controller 120 can also quantitatively estimate the health state SOH of the secondary battery B using the estimated resistance of the secondary battery B. [

As an example, the health state (%) of the secondary battery B can be calculated using the following equation.

Health status (SOH) = 100 * (R _{@ BOL} / R _{@ SOC, T} )

In the above equation, R _{@ SOC, T} is estimated by the present invention as the resistance of the secondary battery B corresponding to the present charging state and temperature of the secondary battery B. [ And R _@ BOL represents the BOL resistance stored in the memory unit 110.

According to another aspect, the controller 120 may be coupled to the communication interface 160 and may communicate at least one of the estimated resistance value, output value, and health state values to an external device ) Side.

Preferably, the external device may be a controller of a load device that receives electric energy from the secondary battery B, but the present invention is not limited thereto.

On the other hand, the resistance of the secondary battery B increases as the degradation of the secondary battery B progresses. Therefore, the resistance profile as shown in Fig. 3 moves upward as the degradation degree of the secondary battery B increases. In addition, the degeneration degree of the secondary battery (B) varies depending on the charging and discharging conditions of the secondary battery (B). For example, the degeneration rate of the secondary battery B varies depending on the temperature at which charge and discharge are performed.

Therefore, the present invention can further consider a parameter called a degradation acceleration index (%) defined by the following equation when estimating the resistance of the secondary battery (B).

Degradation acceleration index = 100 * (R _{@ SOC_ref, T_ref} / R _{@ SOC_ref, T_com} )

In the above equation, R _{@ SOC_ref and T_ref} are resistance values when the state of charge and temperature of the secondary battery correspond to the reference SOC and the reference temperature, respectively. As an example, the reference SOC and the reference temperature may be 50% and 25 ° C, respectively.

A concrete method for the _{R_SOC_ref and T_ref} to be determined by the controller 120 _{and stored} in the memory unit 110 has been described above.

R _{@ SOC_ref T_com} represents a resistance value when the charging state of the secondary battery corresponds to the reference SOC, but is a comparative temperature at which the temperature is considerably higher than or substantially lower than the reference temperature, for example, when the secondary battery B is at 0 캜.

Wherein R _{@SOC_ref,} the determination method of _{T_com} is substantially the same as the R _{@SOC_ref,} the _{T_ref} determination method. That is, the controller 120 monitors the current charging state and the temperature of the secondary battery B stored in the memory unit 110 _, and if the condition for calculating R _{@ SOC_ref and T_com} is established, The measured value of the charged or discharged current and the measured voltage value before and after the corresponding current flows when the charging state and the temperature of the secondary battery B correspond to the reference SOC and the comparative temperature, And R _{@ SOC_ref, T_com} can be calculated by the Ohm's law using the change amount of the measured voltage measurement value and the current measurement value.

4, each resistance lookup table stored in the memory unit 110 includes a resistance increase rate of the reference resistance and a degradation acceleration index As shown in FIG.

The degradation acceleration index illustrated in FIG. 4 is calculated by using resistance values R _{@ SOC_50%, T_25 DEG C,} and R _{@ SOC_50% and T_0.degree} . It is also apparent that the resistance look-up tables of Fig. 4 can be preset through experiments.

Also, when the resistance increase rate and the degradation acceleration index with respect to the reference resistance are determined, the controller 120 identifies the resistance lookup table corresponding to the resistance increase rate and the degradation acceleration index determined in the resistance lookup tables stored in the memory unit 110 , The identified resistance lookup table is designated as a resistance lookup table to be used for estimating the resistance of the secondary battery B, the resistance of the secondary battery B corresponding to an arbitrary charging state and temperature is estimated with reference to the designated resistance lookup table , And store the estimated resistance value in the memory unit 110.

4, when the resistance increase rate and the degradation acceleration index of the reference resistance are 10% and 70%, respectively, and the present charging state and temperature of the secondary battery B are 60% and 20 ° C., respectively, (B) can be estimated to be 1.2 m ?.

The control unit 120 may determine the output or health state of the secondary battery B using the resistance value stored in the memory unit 110 and may store the result in the memory unit 110, And transmit at least one of the estimated resistance, output, and health state to the external device side.

The control unit 120 may be implemented as a processor, an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, a data processing apparatus, and the like known in the art for executing the various control logic As shown in FIG.

Also, when the control logic is implemented in software, the control unit 120 may be implemented as a set of program modules. At this time, the program module is stored in the memory unit 110 and can be executed by the processor. The memory unit 110 may be internal or external to the processor, and may be coupled to the processor by various well known means.

Hereinafter, a method of estimating the resistance of the secondary battery according to the present invention will be described in detail with reference to FIGS. 5 and 6 based on the above-described configuration.

5 is a flowchart illustrating a method of estimating a resistance of a secondary battery according to an embodiment of the present invention.

First, the control unit 120 refers to the current measurement value of the secondary battery B stored in the memory unit 110 to check whether charging / discharging of the secondary battery B has started (S10).

If charging / discharging is started, the control unit 120 controls the voltage measuring unit 130 to measure the open-circuit voltage of the secondary battery B and stores the open-circuit voltage in the memory unit 110 (S20).

The control unit 120 controls the voltage measuring unit 130, the current measuring unit 140 and the temperature measuring unit 150 to measure the voltage, current, and temperature of the secondary battery B, The measured value and the measured temperature value are stored in the memory unit 110 (S30).

Next, the controller 120 determines an initial charge state (SOC ₀ ) corresponding to the open-circuit voltage measured in step S20 using the 'OCV-SOC lookup table' stored in the memory unit 110, ₀ ) of the secondary battery to determine the state of charge of the secondary battery, and stores it in the memory unit 110 (S40).

Next, the control unit 120 determines whether the state of charge and temperature of the secondary battery B stored in the memory unit 110 correspond to the reference SOC and the reference temperature (S50).

In this embodiment, the reference SOC and the reference temperature may be 50% and 25 ° C, respectively.

If the charging state and the temperature of the secondary battery B correspond to the reference SOC and the reference temperature, the control unit 120 determines whether the voltage measurement value and the current measurement value to be used for determining the reference resistance are stored in the memory unit 110 (S60).

If the voltage measurement value and the current measurement value to be used for determining the reference resistance are stored in the memory unit 110, the control unit 120 determines that the charging state and the temperature of the secondary battery B correspond to the reference SOC and the reference temperature The reference resistance of the secondary battery (B) is determined by identifying the measured value of the charged or discharged current and the measured voltage value before and after the current flows, dividing the variation of the voltage measurement value by the current measurement value, In the memory unit 110 (S70).

The control unit 120 determines the rate of increase in resistance with respect to the reference resistance based on the BOL resistance of the secondary battery B stored in the memory unit 110 and stores the determined rate of increase in resistance in the memory unit 110 ).

Then, the control unit 120 determines whether the resistance increase rate calculated in step S80 exceeds a predetermined threshold value (S90).

Here, when the resistance increase rate exceeds the threshold value, it means that it is necessary to update the designation of the resistance lookup information (table) used in the past to estimate the resistance of the secondary battery B.

The period of updating the designation of the resistance lookup table may vary depending on the threshold value to be compared with the resistance increase rate. As an example, the update period may be from several days to several months, but the present invention is not limited thereto.

If the resistance increase rate exceeds a predetermined threshold value, the controller 120 identifies a resistance lookup table corresponding to the resistance increase rate determined in step S80 among a plurality of resistance lookup tables (FIG. 2) stored in the memory unit 110 (S100).

Then, the control unit 120 changes the previously-designated resistance look-up table to the resistance look-up table identified in step S100 for estimating the resistance of the secondary battery B (S110).

If it is determined in step S90 that the resistance increase rate does not exceed the threshold value, the controller 120 determines that the degradation of the secondary battery B has not progressed enough to change the resistance lookup table, and proceeds to step S170.

If the resistance lookup table used for estimating the resistance of the secondary battery B is changed in step S110, the controller 120 measures the magnitude of the charging or discharging current of the secondary battery B through the current measuring unit 140 It is determined whether the charging / discharging of the secondary battery B continues (S120).

If the charge / discharge continues, the control unit 120 moves the process to step S30, and if the charge / discharge is reversed, ends the resistance estimation process according to the present invention.

The above-described embodiment discloses how the resistance lookup table used for estimating the resistance of the secondary battery B is updated when the rate of increase in resistance with respect to the reference resistance of the secondary battery B exceeds the threshold value.

Next, a process of estimating the resistance of the secondary battery B corresponding to an arbitrary charging state and temperature will be described in detail.

The control unit 120 may execute steps S130 through S190 in parallel in addition to the process of updating the resistance lookup table used in estimating the resistance of the secondary battery B. [

First, the control unit 120 determines whether a preset resistance estimation period has elapsed (S130). Here, the resistance estimation period may be arbitrarily determined according to the purpose of utilizing the resistance.

For example, if the resistance of the secondary battery B is estimated for the purpose of utilizing the resistance to estimate the output of the secondary battery B, the resistance estimation period may be set to several seconds to several tens seconds. As another example, if the resistance of the secondary battery B is estimated for the purpose of utilizing the resistance to estimate the health state of the secondary battery B, the resistance estimation period can be set to several minutes to several days. However, the present invention is not limited thereto.

If it is determined that the resistance estimation period has elapsed, the controller 120 determines whether the designation of the resistance lookup table used for estimating the resistance of the secondary battery B is updated (S140).

If the designation of the resistance lookup table is updated, the control unit 120 reads the latest value of the charged state and the temperature of the secondary battery stored in the memory unit 110, and then reads out the plurality of lookups stored in the memory unit 110 The resistance of the secondary battery B is estimated by identifying a designated resistance look-up table in the table and mapping a resistance value corresponding to the read charging state and temperature from the identified resistance look-up table (S150).

The control unit 120 may also store the resistance estimated in step S150 in the memory unit 110 or output it to the external device via the communication interface 160 or use the estimated resistance to determine the output or health of the secondary battery B Other parameters such as the state may be estimated (S160).

Then, the control unit 120 checks whether or not the loop execution cycle has elapsed (S170). If the loop execution cycle has elapsed, the process proceeds to step S120.

On the other hand, if the designation of the resistance lookup table is not updated, the controller 120 identifies an existing resistance lookup table among the plurality of resistance lookup tables stored in the memory unit 110, The resistance of the secondary battery B is estimated by mapping a resistance value corresponding to the read charged state and temperature (S180).

The control unit may also store the resistance estimated in step S180 in the memory unit 110 or transmit it to the external device via the communication interface 160 or use the estimated resistance to measure the output of the secondary battery B, Other parameters may be estimated (S190).

Then, the controller 120 moves the process to step S120 and checks whether the charging / discharging is continued. Then, the controller 120 repeats the algorithm illustrated in FIG. 5 again or finishes the execution of the algorithm.

6 is a flowchart showing a method of estimating a resistance of a secondary battery according to a modified embodiment of the present invention.

The variant of FIG. 6 differs only in that it additionally takes into account the degeneration acceleration index, and the remaining steps are substantially the same as the previously described embodiment.

Therefore, the following description will focus on the steps that are different from the above-described embodiments.

First, the controller 120 estimates the state of charge of the secondary battery B in step S40 and stores it in the memory 110, and then determines whether the estimated state of charge corresponds to the reference SOC (P50). In this modification, the reference SOC is 50% as in the above embodiment.

Next, when the state of charge of the secondary battery B corresponds to the reference SOC, the reference voltage and the current measured value stored in the memory unit 110 are referenced to determine the reference resistance and the comparison resistance of the secondary battery B. It is determined whether there is data (P60).

Here, the reference resistance and the comparison resistance denote R _{@ SOC_ref, T_ref,} and R _{@ SOC_ref} and _{T_com,} respectively. The meaning of each resistance parameter has been described above.

In one example, the data used when determining R _{@ SOC_ref, T_ref} is the measured value of the charged or discharged current when the charged state of the secondary battery B is 50% and the temperature of the secondary battery B is 25 DEG C And two voltage measurement values measured before and after the current flows.

The data used to determine R _{@ SOC_ref and T_com} are the measured values of the charged or discharged current when the state of charge of the secondary battery B is 50% and the temperature of the secondary battery B is 0 DEG C, It may be two voltage measurement values measured before and after the current flows.

If it is determined that there is data necessary for determining the reference resistance and the comparison resistance, the controller 120 determines the reference resistance and the comparison resistance of the secondary battery by dividing the change amount of the voltage measurement value by the current measurement value, (P70).

Next, the control unit 120 calculates a resistance increase rate with respect to the reference resistance determined in step P70 based on the preset BOL resistance of the secondary battery B, and determines the degradation acceleration index from the reference resistance and the comparison resistance by the above- And stores it in the memory unit 110 (P80).

The control unit 120 checks whether the rate of increase of the resistance is greater than the threshold value and determines that the resistance increase rate is greater than the threshold value at step P80 among the plurality of resistance lookup tables stored in the memory unit 110 And the resistance lookup table corresponding to the degradation acceleration index is identified and the designation of the resistance lookup table used for estimating the resistance of the secondary battery B is updated with the identified resistance lookup table at step S110.

On the other hand, the process of estimating the resistance of the secondary battery B corresponding to an arbitrary charging state and temperature after the designation of the resistance lookup table is updated is substantially the same as the above-described embodiment, do.

At least one of the control logic illustrated in FIGS. 5 and 6 may be combined, and the combined control logic may be written in a computer-readable code system and recorded in a computer-readable recording medium.

The type of the recording medium is not particularly limited as long as it can be accessed by a processor included in the computer. As one example, the recording medium includes at least one selected from the group including a ROM, a RAM, a register, a CD-ROM, a magnetic tape, a hard disk, a floppy disk and an optical data recording apparatus. In addition, the code system may be modulated with a carrier signal and included in a communication carrier at a specific point in time, and distributed and stored in a computer connected to the network. Also, functional programs, code, and code segments for implementing the combined control logic can be easily inferred by programmers skilled in the art to which the present invention pertains.

The apparatus for estimating the resistance of a secondary battery according to the present invention may be included as a part of a system called a BMS (Battery Management System). In addition, the BMS can be mounted on various kinds of electric driving devices capable of operating with the electric energy provided by the secondary battery (B).

According to an aspect, the electric drive device may be a mobile computer device such as a mobile phone, a laptop computer, a tablet computer, or a handheld multimedia device including a digital camera, a video camera, an audio / video reproducing device and the like.

According to another aspect of the present invention, the electric drive device is an electric drive device that can be moved by electricity such as an electric car, a hybrid car, an electric bicycle, an electric motorcycle, an electric train, an electric boat, an electric plane, Likewise, it can be a power tool with a motor.

According to another aspect of the present invention, the electric drive apparatus includes a large-capacity electric power storage device installed in a power grid for storing renewable energy or surplus generated electric power, or various types of information including a server computer and mobile communication equipment in an emergency, Or an uninterruptible power supply for supplying power to the communication device.

In describing the various embodiments of the present invention, the components labeled 'to' should be understood to be functionally distinct elements rather than physically distinct elements. Thus, each component may be selectively integrated with another component, or each component may be divided into sub-components for efficient execution of the control logic (s). It will be apparent to those skilled in the art, however, that, even if components are integrated or partitioned, the integrity of the functionality can be recognized, it is understood that the integrated or segmented components are also within the scope of the present invention.

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.

B: secondary battery 100: resistance estimating device of a secondary battery
110: memory unit 120: control unit
130: voltage measuring unit 140: current measuring unit
150: Temperature measuring unit 160: Communication interface

Claims (27)

A memory unit storing a plurality of pieces of resistance lookup information that can map a resistance corresponding to a charged state and a temperature of the secondary battery for each resistance increase rate of the secondary battery; And
Determining a reference resistance of the secondary battery from the measured current and voltage when the charged state and temperature of the secondary battery correspond to a preset reference SOC and reference temperature and determining a resistance increase rate of the reference resistor based on the BOL resistance of the secondary battery And a control unit for identifying in the memory unit the resistance lookup information corresponding to the determined resistance increase rate and for estimating the resistance of the secondary battery corresponding to a certain charging state and temperature using the identified resistance lookup information Wherein the resistance estimating device comprises:
The method according to claim 1,
Wherein the reference SOC is 40-60%, and the reference temperature is 20-30 < 0 > C.
The method according to claim 1,
A voltage measuring unit for measuring a voltage of the secondary battery;
A current measuring unit for measuring a current of the secondary battery; And
And a temperature measuring unit for measuring a temperature of the secondary battery,
Wherein the controller is configured to store the voltage measurement value, the current measurement value, and the temperature measurement value in the memory unit.
The method of claim 3,
Wherein the controller is configured to determine a state of charge of the secondary battery by integrating a current measurement value stored in the memory unit.
The apparatus of claim 3,
The method includes identifying a measured value of a current charged or discharged at the reference SOC and a current value measured from the voltage measurement value and the current measurement value stored in the memory unit and identifying two measured voltage values measured before and after the current flows And determine a reference resistance from a change amount of the voltage measurement value and a current measurement value.
The method according to claim 1,
Wherein the resistance lookup information is a resistance lookup table having a data structure capable of mapping a resistance of the secondary battery according to a charged state and a temperature of the secondary battery.
The apparatus of claim 1,
Storing the estimated resistance in the memory unit,
Determining an output of the secondary battery using the estimated resistance,
And to transmit the estimated resistance to an external device.
A memory unit storing a plurality of pieces of resistance lookup information that can map a resistance corresponding to a charged state and a temperature of the secondary battery according to the resistance increase rate and the degradation acceleration index of the secondary battery; And
The reference resistance of the secondary battery is determined from the measured current and voltage when the charged state and temperature of the secondary battery correspond to a preset reference SOC and reference temperature, Determining a comparative resistance of the secondary battery when it is determined, determining a BOL resistance of the secondary battery and a rate of increase in resistance from the reference resistance, determining a degradation acceleration index from a ratio of the reference resistance to the comparison resistance, And a controller for identifying the resistance lookup information corresponding to the degradation acceleration index in the memory unit and for estimating the resistance of the secondary battery corresponding to an arbitrary charging state and temperature from the identified resistance lookup information A device for estimating the resistance of a secondary battery.
9. The method of claim 8,
The reference SOC is 40-60%
The reference temperature is 20-30 DEG C,
Wherein the comparison temperature is in the range of -10 < 0 > C to 10 < 0 > C.
9. The method of claim 8,
A voltage measuring unit for measuring a voltage of the secondary battery;
A current measuring unit for measuring a current of the secondary battery; And
And a temperature measuring unit for measuring a temperature of the secondary battery,
Wherein the controller is configured to store the voltage measurement value, the current measurement value, and the temperature measurement value in the memory unit.
11. The method of claim 10,
Wherein the controller is configured to determine a state of charge of the secondary battery by integrating a current measurement value stored in the memory unit.
11. The apparatus according to claim 10,
The method includes identifying a measured value of a current charged or discharged at the reference SOC and a current value measured from the voltage measurement value and the current measurement value stored in the memory unit and identifying two measured voltage values measured before and after the current flows And to determine a reference resistance from a change amount of the voltage measurement value and a current measurement value,
A reference SOC and a measured value of a current charged or discharged at the comparison temperature among the voltage measurement value and the current measurement value stored in the memory unit and identifies two measured voltage values measured before and after the current flows And the comparison resistance is determined based on a change amount of the voltage measurement value and a current measurement value.
9. The method of claim 8,
Wherein the resistance lookup information is a resistance lookup table having a data structure capable of mapping a resistance of the secondary battery according to a charged state and a temperature of the secondary battery.
9. The apparatus according to claim 8,
Storing the estimated resistance in the memory unit,
Determining an output of the secondary battery using the estimated resistance,
And to transmit the estimated resistance to an external device.
(a) storing in the memory a plurality of pieces of resistance lookup information that can map a resistance corresponding to a charged state and a temperature of the secondary battery, for each resistance increase rate of the secondary battery;
(b) receiving a voltage measurement value, a current measurement value, and a temperature measurement value from the voltage measurement unit, the current measurement unit, and the temperature measurement unit, and storing the received voltage measurement value, current measurement value, and temperature measurement value in the memory unit;
(c) determining a state of charge of the secondary battery using the current measurement value and storing the state of charge in the memory unit;
(d) a measurement value of a charge or discharge current measured when a charge state and a temperature of the secondary battery correspond to a preset reference SOC and a reference temperature among a current measurement value and a voltage measurement value stored in the memory unit, Determining a reference voltage of the secondary battery by using a change amount of the voltage measurement value and the current measurement value;
(e) determining a resistance increase rate of the reference resistor based on a BOL resistance of a predetermined secondary battery;
(f) identifying in the memory unit resistance lookup information corresponding to the resistance increase rate; And
(g) estimating a resistance of the secondary battery corresponding to a certain charging state and a temperature using the identified resistance lookup information.
16. The method of claim 15,
Wherein the reference SOC is 40-60%, and the reference temperature is 20-30 < 0 > C.
16. The method of claim 15,
Wherein the charging state of the secondary battery is determined by integrating the current measurement value in the step (c).
16. The method of claim 15,
Wherein the resistance lookup information is a resistance lookup table having a data structure capable of mapping a resistance of a secondary battery according to a charged state and a temperature of the secondary battery.
16. The method of claim 15,
Storing the estimated resistance in the memory unit;
Determining an output of the secondary battery using the estimated resistance; or
And transferring the estimated resistance to an external device. ≪ Desc / Clms Page number 20 >
(a) storing, in a memory, a plurality of resistance lookup information that can map a resistance corresponding to a charged state and a temperature of a secondary battery according to a resistance increase rate and a degradation acceleration index of the secondary battery;
(b) receiving a voltage measurement value, a current measurement value, and a temperature measurement value from the voltage measurement unit, the current measurement unit, and the temperature measurement unit, and storing the received voltage measurement value, current measurement value, and temperature measurement value in the memory unit;
(c) determining a state of charge of the secondary battery using the current measurement value and storing the state of charge in the memory unit;
(d) determining a reference resistance and a comparison resistance of the secondary battery by identifying the voltage measurement value and the current measurement value respectively measured at the reference temperature and the comparison temperature set in advance when the state of charge of the secondary battery is the reference SOC set in advance, step;
(e) determining a BOL resistance of the secondary battery and a resistance increase rate from the reference resistance;
(f) determining a degradation acceleration index from a relative ratio of the reference resistance and the comparison resistance;
(g) identifying in the memory unit resistance lookup information corresponding to the determined resistance increase rate and the degradation acceleration index; And
(h) estimating a resistance of the secondary battery corresponding to a certain charging state and a temperature using the identified resistance lookup information.
21. The method of claim 20,
The reference SOC is 40-60%
The reference temperature is 20-30 DEG C,
Wherein the comparison temperature is in the range of -10 < 0 > C to 10 < 0 > C.
21. The method of claim 20,
Wherein the charging state of the secondary battery is determined by integrating the current measurement value stored in the memory unit in the step (c).
21. The method of claim 20, wherein step (d)
The reference SOC and the measured value of the current charged or discharged at the reference temperature and the measured voltage value measured before and after the current flows, from the voltage measurement value and the current measurement value stored in the memory unit, ; And
The reference resistance SOC and the reference current SOC of the memory unit are compared with each other using the measured value of the current charged or discharged at the comparison temperature and the measured voltage value measured before and after the current flows, And determining the resistance of the secondary battery.
21. The method of claim 20,
Wherein the resistance lookup information is a resistance lookup table having a data structure capable of mapping a resistance of a secondary battery according to a charged state and a temperature of the secondary battery.
21. The method of claim 20,
Storing the estimated resistance in the memory unit;
Determining an output of the secondary battery using the estimated resistance; or
And transferring the estimated resistance to an external device.
9. A secondary battery management system comprising a resistance estimating device for a secondary battery according to claim 1 or 8.
A computer-readable recording medium storing a method of estimating a resistance of a secondary battery according to claim 15 or 20, which is programmed.

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