KR101065551B1 - Battery capacity estimation device and method - Google Patents

Abstract

The present invention discloses an apparatus and method for estimating capacity of a battery. An apparatus for estimating a capacity of a battery according to the present invention includes an SOC estimator for estimating a state of charge of a battery; An actual capacity estimating unit for quantifying the degradation of the battery by the resistance degradation rate and estimating the actual capacity of the battery based on the initial capacity of the battery; SOC safety margin estimator for estimating the safety margin of the state of charge that can safely use the battery using the resistance degradation rate; A usable capacity estimator for estimating a usable capacity of a battery using the estimated state of charge, actual capacity, and safety margin; And a memory unit for storing the estimated usable capacity.

Description

Apparatus and Method for estimating capacity of battery

The present invention relates to an apparatus and method for estimating battery capacity, and more particularly, to an apparatus and method for accurately estimating the usable capacity of a battery using the resistance of the battery.

In recent years, as air pollution increases and fossil fuels are depleted, electric and hybrid vehicles that can be driven using batteries have attracted attention.

The capacity of the battery decreases with increasing usage time. This is because the performance of the battery decreases with time by the aging effect.

Batteries used in portable devices such as mobile phones have no special problem except that the operation time of the device is reduced even if the capacity is reduced. However, batteries used in electric and hybrid vehicles run out of battery life and can suddenly stop when their capacity drops below the limit. In addition, repeated overcharging or overdischarging exceeding the capacity when the battery capacity falls below the limit may cause serious problems (eg, explosion) in the stability of the battery.

Accordingly, in the battery industry, studies are being actively conducted to quantitatively evaluate the aging effects of battery use. In order to quantitatively evaluate the aging effect of a battery, an electrochemical parameter whose physical properties change with time of use of the battery is required. One of them is the resistance of the battery.

Since the resistance of the battery tends to increase with the usage time of the battery, it is possible to quantitatively evaluate the aging effect of the battery by measuring the resistance of the battery and comparing it with the initial resistance when the battery is shipped.

Battery resistance cannot be measured directly while charging or discharging is taking place. Therefore, conventionally, by measuring the voltage and current of the battery and indirectly estimated the battery resistance by Ohm's law.

However, since the battery voltage shows an error with the actual voltage due to the IR drop effect, and the current of the battery also has a measurement error, the resistance estimated by the Ohm's law simply shows the actual resistance and the error.

Therefore, there is a need in the art for a method of more accurately estimating battery resistance.

For reference, the IR drop phenomenon refers to a phenomenon in which the battery voltage is different from the actual voltage during charging or discharging of the battery.

7 and 8 are graphs showing the IR drop phenomenon that occurs when the battery is charged or discharged.

When the battery is being charged, as shown in FIG. 7, the battery voltage rapidly rises and saturates above the actual voltage, and when the battery is stopped, the battery voltage rapidly descends and saturates.

On the contrary, when the battery is discharged, as shown in FIG. 8, the battery voltage rapidly decreases below the actual voltage and becomes saturated, and when the discharge stops, the battery voltage rises rapidly and then saturates.

Electric and hybrid vehicles, on the other hand, provide the driver with the ability to calculate the distance a battery can drive. Only then can the driver recharge the battery at the appropriate time.

In order to accurately calculate the distance traveled by the battery, it is necessary to know the usable capacity of the battery that can be used for driving and the capacity consumed per unit distance.

The consumed capacity per unit distance varies depending on the specification of the vehicle or the driving habits of the user. Therefore, it can be calculated by averaging the battery output for driving the unit distance for a certain time.

On the other hand, the usable capacity of the battery that can be used for driving is calculated by the following equation (1).

[Equation 1]

Usable capacity = Actual capacity (Ah) State State of charge (SOC)

Here, the actual capacity is a capacity of the battery when the battery is fully charged and reflects the degree of degradation of the battery due to the aging effect. The state of charge represents the state of charge of the battery at the present time. Available capacity and actual capacity are expressed in Ah and the state of charge is expressed in%. A state of charge of A% means that the current battery has a charge capacity equal to A% of the actual capacity.

The actual capacity of the battery tends to decrease gradually as the battery degrades due to the aging effect. Therefore, the actual capacity of the battery needs to be calculated by reflecting the decrease in capacity due to the deterioration of the battery in the initial capacity of the battery.

In addition, the internal resistance increases as the battery degenerates. This increase in internal resistance causes a deepening of the IR drop phenomenon. In other words, when the internal resistance increases, a larger voltage change occurs even with a charge / discharge current change of the same magnitude. Therefore, as the battery degenerates, as the state of charge approaches 100% or near 0%, a sudden voltage change is caused by the deepening of the IR drop phenomenon. As a result, the battery voltage may change below the charge upper limit voltage or below the discharge lower limit voltage, thereby causing problems in battery stability.

Therefore, when calculating the usable capacity of the battery according to Equation 1, it is necessary to set the safety margin of the state of charge that can be actually used in consideration of the voltage variation that may occur due to the IR drop phenomenon near the upper and lower limits of the state of charge. .

The present invention was devised to solve the above problems of the prior art, and accurately estimates the usable capacity of a battery by setting a safety margin in a state of charge in which the battery can be used safely in consideration of the degradation of the battery and the IR drop phenomenon. It is an object of the present invention to provide an apparatus and method capable of doing so.

Another object of the present invention is to provide an apparatus and method for estimating the range of driving of a battery-mounted driving device using the accurately estimated usable capacity of the battery.

According to an aspect of the present invention, there is provided an apparatus for estimating a capacity of a battery, the SOC estimator configured to estimate a state of charge of the battery; An actual capacity estimating unit for quantifying the degradation of the battery by the resistance degradation rate and estimating the actual capacity of the battery based on the initial capacity of the battery; SOC safety margin estimator for estimating the safety margin of the state of charge that can safely use the battery using the resistance degradation rate; A usable capacity estimator for estimating a usable capacity of a battery using the estimated state of charge, actual capacity, and safety margin; And a memory unit for storing the estimated usable capacity.

In addition, the method for estimating the capacity of a battery according to the present invention for achieving the above technical problem, estimating the state of charge of the battery; Quantifying the degradation of the battery by the resistance degradation rate and estimating the actual capacity of the battery based on the initial capacity of the battery; Estimating a safety margin of a state of charge capable of safely using the battery using the resistance degradation rate; Estimating the usable capacity of the battery using the estimated state of charge, actual capacity, and safety margin; And storing the estimated usable capacity.

The object of the invention can also be achieved by a battery management device, a battery driven device or a battery comprising an apparatus for estimating usable capacity of a battery according to the invention.

According to an aspect of the present invention, it is possible to accurately estimate the usable capacity of the battery by setting the safety margin of the state in which the battery can be safely used by reflecting the degradation of the battery and the IR drop phenomenon.

According to another aspect of the present invention, as the state of charge approaches 100% or 0%, even if the voltage is drastically changed by the IR drop effect, it is possible to ensure the stability of the battery.

According to still another aspect of the present invention, it is possible to accurately estimate the driving distance of the battery driving apparatus in which the battery is mounted within the range in which the battery can be safely used.

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.
1 is a block diagram illustrating a configuration of an apparatus for estimating a capacity of a battery according to an exemplary embodiment of the present invention.
2 is a block diagram showing the configuration of a control unit according to an embodiment of the present invention.
3 is a flowchart illustrating a flow of a method for estimating battery capacity according to an exemplary embodiment of the present invention.
4 is a graph showing a phenomenon in which the actual capacity of the battery gradually decreases based on the initial capacity as the charge and discharge cycle of the battery increases.
5 is a graph illustrating a case in which the upper and lower limits of the state of charge are adjusted as the resistance is increased due to the degeneration of the battery, thereby setting the upper and lower limits of the safety margin.
6 is a graph showing a profile of a first correction coefficient calculation function and a second correction coefficient calculation function using the resistance decay rate as an input variable.
7 and 8 are graphs showing the IR drop phenomenon that occurs when the battery is charged and discharged, respectively.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

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

Referring to FIG. 1, an apparatus for estimating a capacity of a battery according to the present invention is connected between a battery 100 and a load 107, and includes a voltage detector 101, a temperature detector 102, a current detector 103, and a memory. The unit 104 and the control unit 105 is included.

The voltage detector 101 periodically measures the battery voltage under the control of the controller 105 and outputs the battery voltage to the controller 105. The voltage detector 101 includes a voltage measuring circuit for measuring a battery voltage. The voltage measuring circuit uses a circuit known in the art.

The temperature detector 102 periodically measures the battery temperature under the control of the controller 105 and outputs the battery temperature to the controller 105. The temperature detector 102 includes a known temperature measuring element such as a thermo coupler.

The current detector 103 periodically measures the battery current flowing through the current detection resistor 108 under the control of the controller 105 and outputs the current to the controller 105. The battery current is a charge current or a discharge current.

The memory unit 104 stores battery voltage, temperature, and current data measured by the voltage detector 101, the temperature detector 102, and the current detector 103. The memory unit 104 also stores various lookup tables described below. Further, the memory unit 104 stores various programs and data necessary in advance in estimating the program required for the operation of the controller 105 and the usable capacity of the battery or the driving distance.

The controller 105 controls the voltage detector 101, the temperature detector 102, and the current detector 103 to receive periodically measured battery voltage, temperature, and current data and store the measured data in the memory unit 104.

In addition, the controller 105 stores various calculated values generated in the process of estimating the usable capacity of the battery and the available distance, and the estimated usable capacity and the available distance in the memory unit 104.

In addition, the controller 105 outputs the estimated usable capacity or travelable distance to the outside through the display unit 106. Alternatively, the controller 105 may transmit the estimated usable capacity or travelable distance to the external device through the communication interface 109.

The type of the battery 100 is not particularly limited, and may be configured as a lithium ion battery, a lithium polymer battery, a nickel cadmium battery, a nickel hydride battery, a nickel zinc battery, and the like, which can be recharged and require a state of charge.

The type of the load 107 is not particularly limited, and may be configured as a portable electronic device such as a video camera, a portable telephone, a portable PC, a PMP, or an MP3 player, a motor of an electric vehicle or a hybrid vehicle, a DC to DC converter, or the like. .

2 is a block diagram showing the configuration of the control unit 105 according to an embodiment of the present invention.

Referring to FIG. 2, the control unit 105 includes an SOC estimator 202, a resistance degradation estimator 203, an actual capacity estimator 204, an SOC safety margin estimator 205, and an available capacity estimator ( 206).

The SOC estimator 202 estimates the state of charge of the battery. Here, SOC stands for 'State Of Charge'. The SOC estimator 202 estimates the state of charge of the battery using the battery voltage, temperature, current data or a combination thereof stored in the memory unit 104.

The SOC estimator 202 may estimate the state of charge of the battery by employing any method known in the art.

For example, the SOC estimator 202 may estimate the state of charge of a battery using the 'battery open voltage estimating apparatus, a battery charge state estimating apparatus using the same, and a control method thereof' disclosed in Korean Patent Publication No. 10-2009-0020470. Can be.

As another example, the SOC estimator 202 is disclosed in the method for calculating the remaining capacity of a battery pack, a method for determining an open voltage used in the calculation method, and the device disclosed in Korean Patent Publication No. 10-2008-0014207. The method can be used to estimate the state of battery charge.

As another example, the SOC estimator 202 uses a method disclosed in Korean Patent Publication Nos. 10-2001-0043872, 10-2005-0019856, 10-2007-0106758, 10-2008-0088617, 10-2009-0117835, and the like. It is possible to estimate the state of charge of the battery.

In addition to the above, the method of estimating the state of charge of the battery by the SOC estimator 202 may be variously modified. Therefore, the present invention is not limited to the specific manner in which the SOC estimator 202 estimates the state of charge of the battery. And the invention disclosed in the above-mentioned patent publications may be included as part of the present invention.

The resistance decay estimator 203 estimates the resistance of the battery. Here, the estimated resistance is the resistance at the present time in which the deterioration of the battery is reflected.

The resistance decay estimator 203 estimates the resistance of the battery using the battery voltage, temperature, current data, or a combination thereof stored in the memory 104.

The resistance degradation estimation unit 203 may estimate the resistance of the battery by employing any method known in the art.

For example, the resistance decay estimator 203 may estimate the resistance of the battery using the “apparatus and method for estimating battery resistance using battery voltage behavior” disclosed in Korean Patent Publication No. 10-0927541.

As another example, the resistance decay estimator 203 may estimate the resistance of the battery using the 'apparatus and method for estimating battery resistance using battery voltage behavior' disclosed in Korean Patent Publication No. 10-0911315.

As another example, the resistance decay estimator 203 may estimate the battery resistance based on Ohm's law from the most recent battery voltage and current stored in the memory 104.

As another example, the resistance degradation estimation unit 203 may estimate the battery resistance with reference to the resistance estimation lookup table stored in the memory unit 104.

That is, the memory unit 104 may store a resistance estimation lookup table defining resistances according to various voltages, currents, and temperatures of the battery. The resistance estimation lookup table may be obtained through an experiment of measuring the resistance of the battery according to a change in voltage, current, and temperature of the battery. The resistance degradation estimator 203 may estimate a resistance corresponding to the most recent battery voltage, current, and temperature with reference to the resistance estimation lookup table stored in the memory unit 104.

In addition to the above, the method of estimating the resistance by the resistance deterioration estimator 203 may be modified in various ways. Therefore, the present invention is not limited by the specific manner in which the resistance deterioration estimator 203 estimates the resistance of the battery. And the invention disclosed in the above-mentioned patent publications may be included as part of the present invention.

After the resistance decay estimator 203 estimates the resistance of the battery, the resistance decay rate is estimated by calculating a relative ratio of the resistance estimated based on the initial resistance of the battery.

The resistance degradation rate can be calculated by the following equation (2).

[Equation 2]

Resistance degradation rate R _D = R _estimated / R _initial

Where R _estimated is the estimated resistance and R _initial is the initial resistance at the time the battery is shipped. The R _initial is stored in the memory unit 104 in advance and is referred to when estimating the resistance degradation rate.

The actual capacity estimating unit 204 estimates the actual capacity of the battery in consideration of the degree of resistance degradation of the battery.

For example, the actual capacity estimating unit 204 estimates the actual capacity of the battery by the following equation (3).

&Quot; (3) "

Actual capacity C _actual (Ah) = F (A) ⅹC _initial

Here, C _initial is an initial capacity at the time the battery is shipped, and is stored in the memory unit 104 in advance and is referred to when estimating the actual capacity.

F (A) is a coefficient function for converting an initial capacity of a battery into an actual capacity. The coefficient function is a function using parameter A as a variable.

Preferably, the parameter A includes a resistance degradation rate. Alternatively, the parameter A may further include a temperature in addition to the resistance degradation rate.

The function F can be obtained by experimenting to fully charge a plurality of batteries that know the resistance degradation rate in advance, and measuring the battery capacity and numerically analyzing the correlation between the resistance degradation rate and the battery capacity.

When the temperature of the parameter A is further included, the function F measures the battery capacity by experimenting to fully charge a plurality of batteries having a known resistance degradation rate in various temperature conditions, and measures the resistance degradation rate and the temperature and the battery capacity. The relationship can be found by numerical analysis.

In an alternative embodiment, the actual capacity estimating unit 204 may estimate the actual capacity of the battery with reference to the capacity estimation lookup table stored in the memory unit 104.

That is, the memory unit 104 may store a capacity estimation lookup table that defines actual capacity for each capacity decay rate of the battery. Alternatively, the memory unit 104 may store a capacity estimation lookup table that defines actual capacity for each capacity decay rate and temperature of the battery. The latter capacity estimation lookup table may have a data structure in which a plurality of temperature conditions correspond to one resistance degradation rate, and actual capacity is defined for each temperature condition.

The actual capacity estimating unit 204 may estimate the actual capacity corresponding to the resistance decay rate or the resistance decay rate and the temperature with reference to the capacity estimation lookup table stored in the memory 104. Here, the resistance degradation rate is the resistance degradation rate estimated by Equation 2, and the temperature is the temperature of the battery stored in the memory unit 104.

On the other hand, as the battery ages, the resistance increases, and the actual capacity gradually decreases. 4 is a graph showing a phenomenon in which the actual capacity of the battery gradually decreases based on the initial capacity as the charge and discharge cycle of the battery increases.

Referring to FIG. 4, it can be seen that the actual capacity of the battery gradually decreases as the charge / discharge cycle of the battery increases to 0, 300, 500, and 700 cycles.

In addition, if the resistance of the battery is increased, the IR drop phenomenon is intensified, so that the voltage change range is larger even with a current change of the same magnitude. If you use the battery until the charge is near 100% or 0%, there is a safety problem.

If the voltage suddenly increases when the state of charge approaches 100% due to the IR drop, the battery voltage exceeds the upper limit of charge. In addition, if the voltage drops sharply due to IR drop when the state of charge approaches 0%, the battery voltage drops below the lower limit of charge.

Therefore, when the battery degenerate, it is necessary to adjust the upper limit of the state of charge lower than 100% and the lower limit of the state of charge higher than 0% according to the degree of degeneration.

Hereinafter, the upper limit of the state of charge controlled lower than 100% as described above will be defined as the safety margin upper limit, the lower limit of the state of charge controlled higher than 0% will be defined as the safety margin lower limit.

5 is a graph illustrating a case in which the upper and lower limits of the state of charge are adjusted as the resistance is increased due to the degeneration of the battery, thereby setting the upper and lower limits of the safety margin.

Referring to FIG. 5, it can be seen that the safety margin of the charged state is reduced compared to the initial safety margin due to the deterioration of the battery.

The SOC safety margin estimator 205 estimates the safety margin upper limit and the lower limit of the state of charge which can be safely used by considering the deterioration rate of the battery using the resistance deterioration rate as a parameter and stores the safety margin in the memory unit 104.

The SOC safety margin estimator 205 may calculate a safety margin upper limit (SM _upper ) and a lower limit (SM _lower ) using Equation 4 below.

&Quot; (4) "

SM _upper = RD ^-1 ⅹ 1st correction factor

SM _lower = RD ⅹ 2nd correction factor

Here, RD is a resistance decay rate, and the first and second correction coefficients are correction coefficients for mitigating a sudden decrease in the upper safety margin and a sharp increase in the lower safety margin.

Table 1 shows an example in which the upper and lower limits of the first and second correction factors and safety margins are specifically calculated according to the resistance degradation rate. The data structure shown in Table 1 may be stored in the memory unit 104 as a safety margin lookup table.

TABLE 1

The first and second correction coefficients and the safety margin upper and lower limits corresponding to the resistance decay rates shown in Table 1 may be obtained by performing a charge / discharge test using a plurality of batteries having a known resistance decay rate.

In charge-discharge experiments, the Urban Dynamometer Driving Cycle (UDDS), Highway Fuel Economy Driving Schedule (HWFET), NYCC, as defined by the US Environmental Protection Agency (EPA), which is the standard for vehicle testing in the electric or hybrid vehicle industry. The battery can be charged and discharged by continuously applying a vehicle driving model according to the (New York City Cycle Driving Schedule) and the US60 (Aggressive Driving Cycle).

Here, the UDDS and NYCC is a standardized vehicle driving model assuming a state change of the vehicle that the vehicle receives when the HWFET operates the vehicle on the highway, the US60 operates the vehicle at high speed when the vehicle is driven in the city center to be.

According to an aspect of the present invention, the SOC safety margin estimator 205 obtains first and second correction factors corresponding to the estimated resistance degradation rate by referring to the safety margin lookup table stored in the memory unit 104. By using Equation 4, the upper and lower safety margins can be calculated.

According to another aspect of the present invention, the SOC safety margin estimator 205 may directly obtain a safety margin upper limit and a lower limit corresponding to the estimated resistance degradation rate with reference to the safety margin lookup table stored in the memory unit 104. .

Alternatively, the relationship between the resistance degradation rate and the first correction factor and the second correction factor may be expressed as a function.

6 is a graph showing a profile of a first correction coefficient calculation function and a second correction coefficient calculation function using the resistance decay rate as an input variable.

In an alternative embodiment, the SOC safety margin estimator 205 substitutes the resistance degradation rate into the first correction coefficient calculation function and the second correction coefficient calculation function as shown in FIG. 6 to correspond to the resistance degradation rate. Calculate the 1st correction factor and the 2nd correction factor. Then, the SOC safety margin estimator 205 calculates a safety margin upper limit and a lower limit corresponding to the resistance degradation rate estimated by Equation (4).

It is common in the art that the safety margin lookup table and the first and second correction coefficient calculation functions representing the relationship between the resistance degradation rate and the first and second correction coefficients may vary depending on the type or specification of the battery. Self-explanatory to those who have knowledge.

The usable capacity estimating unit 206 can use a battery that can be used to drive a battery-mounted driving device using the estimated actual capacity, the upper and lower limits of the estimated safety margin, and the estimated state of charge. Estimate the dose.

The usable capacity estimating unit 206 estimates the usable capacity of the battery according to Equation 5 below and stores it in the memory unit 104.

[Equation 5]

Usable capacity (Ah) = Actual capacity (Ah) ⅹ (upper safety margin%-lower safety margin%) ⅹ state of charge (%)

The usable capacity estimating unit 206 may output the estimated usable capacity through the display unit 106. Then, the display unit 106 may display the available capacity as a percentage based on the actual capacity as a percentage, or a graphic user interface such as a bar graph. Alternatively, the usable capacity estimator 206 may transmit the estimated usable capacity of the battery to the external device through the communication interface 109.

The control unit 200 according to the present invention may further include a data storage unit 201. The data storage unit 201 periodically receives data regarding battery voltage, temperature, and current from the voltage detector 101, the temperature detector 102, and the current detector 103 shown in FIG. Store in

In addition, the control unit 200 according to the present invention may further include a driving distance estimating unit 207.

The driving distance estimating unit 207 estimates the driving distance of a driving device (eg, a vehicle) equipped with a battery using the estimated usable capacity and stores the driving distance in the memory unit 104.

The driving distance estimating unit 207 may estimate the driving distance based on Equation 6 below.

&Quot; (6) "

Travelable distance = usable capacity (Ah) / consumed capacity per unit distance (1 km) (Ah)

The travelable distance estimator 207 may output the estimated travelable distance through the display unit 106. Then, the display unit 106 displays the driving distance numerically to the driver. Alternatively, the travelable distance estimator 207 may transmit the estimated travelable distance to an external device through the communication interface 109.

According to an aspect of the present invention, the controller 140 may be configured as a microprocessor. In this case, components of the controller 140 may be implemented as program modules. The program module may be embodied in the form of program instructions that can be executed by computer means and recorded in a computer-readable medium.

The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those skilled in the computer program arts.

The computer readable recording medium includes a memory unit 104. Computer-readable recording media also include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Hardware devices specially configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory and the like.

Examples of program instructions include machine code, such as produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter.

According to another aspect of the present invention, the components of the controller 105 described above may be embodied as an electronic circuit module including a logic circuit. An example of an electronic circuit module is an application specific semiconductor (ASIC). However, the present invention is not limited thereto.

The battery usable capacity estimating apparatus according to the present invention may be used in combination with a battery pack driving apparatus powered from a battery.

As an example, the present invention may be used in combination with various power units equipped with batteries such as fossil fuel vehicles, electric vehicles, hybrid vehicles, and electric bicycles.

However, the present invention is not suggested to be used in a variety of electronic products that receive a driving voltage from a battery, such as a laptop, a mobile phone, a personal portable multimedia player.

Furthermore, the battery usable capacity estimating apparatus according to the present invention can be modularized into a PCB circuit or an application specific semiconductor circuit (ASIC) and mounted in a battery or a battery management apparatus.

3 is a flowchart illustrating a flow of a method for estimating battery capacity according to an exemplary embodiment of the present invention.

As shown in the figure, when the process for calculating the usable capacity of the battery is started, first, in step S10, the controller 105 estimates the state of charge of the battery and stores it in the memory unit 104. Here, the method of estimating the state of charge of the battery is the same as already described.

Then, in step S20, the controller 105 estimates the battery resistance, estimates the resistance decay rate, and stores it in the memory unit 104. Here, the method of estimating the battery resistance and the resistance degradation rate is the same as described above.

Then, in step S30, the controller 105 estimates the actual capacity of the battery using the estimated resistance degradation rate and stores it in the memory. Here, the actual capacity estimation method is the same as described above.

Next, in step S40, the controller 105 estimates an upper and lower safety margin for the state of charge of the battery by using the estimated resistance decay rate, the first correction factor, and the second correction factor to the memory unit 104. Save it. Here, the method of estimating the safety margin upper limit and the lower limit is the same as already described.

Subsequently, in step S50, the controller 105 estimates the usable capacity of the battery using the estimated actual capacity, the estimated state of charge, and the estimated safety margin upper and lower limits, and stores it in the memory unit 104.

Step S60 is an optional step, and the controller 105 may output the estimated usable capacity of the battery to the display unit 106. Then, the display unit 106 may receive the available capacity of the battery and display a relative ratio based on the initial capacity of the battery as a percentage or in the form of a bar graph by a graphic user interface. Alternatively, in step S60, the controller 105 may transmit the estimated available capacity to the external device through the communication interface.

On the other hand, the control unit 105 may further proceed to the step of estimating the driving distance after step S60. That is, in step S70, the controller 105 estimates the travelable distance by using the estimated usable capacity and the consumed capacity per unit distance of the driving apparatus equipped with the battery, and stores it in the memory unit 104.

Step S80 is an optional step to be performed, and the controller 105 may output the estimated travelable distance through the display unit 106. Alternatively, the controller 105 may transmit data about the estimated range of travel to an external device through a communication interface.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

100: battery 101: voltage detector
102: temperature detector 103: current detector
104: memory unit 105: control unit
106: display unit 107: load
108: sense resistor 109: communication interface
201: data storage 202: SOC estimator
203: resistance deterioration estimator 204: actual capacity estimator
205: SOC safety margin estimation unit 206: usable capacity estimation unit
207: driving distance estimation unit

Claims (26)

An SOC estimator estimating a state of charge of the battery;
An actual capacity estimator for estimating an actual capacity of the battery by decreasing an initial capacity of the battery according to an increase in the resistance degradation rate;
SOC safety margin estimator for estimating by reducing the safety margin of the state of charge that can safely use the battery as the resistance degradation rate increases;
A usable capacity estimating unit estimating the usable capacity by reflecting a decrease of the estimated safety margin when estimating a usable capacity of a battery from the estimated state of charge and the actual capacity; And
And a memory unit for storing the estimated usable capacity. The method of claim 1,
And a resistance decay estimator estimating a resistance decay rate by estimating a resistance of the battery and calculating a relative ratio of the estimated resistance based on the initial resistance of the battery. The method of claim 1,
The actual capacity estimating unit,
Equation:
Actual capacity C _actual (Ah) = F (A) ⅹC _initial
Where C _initial is the initial capacity of the battery, F (A) is a coefficient function that converts the initial capacity of the battery into actual capacity, and is a function that predefines the reduction pattern of the actual battery capacity as the resistance deterioration rate increases. A is a parameter that affects the reduction of the actual battery capacity, including the resistance decay rate)
Estimating the actual capacity of the battery by the battery capacity estimation apparatus. The method of claim 3,
The parameter A further comprises a battery temperature. The method of claim 1,
The actual capacity estimating unit estimates an actual capacity corresponding to the capacity decay rate with reference to a capacity estimation lookup table that defines the actual capacity for each capacity decay rate. The method of claim 1,
The actual capacity estimating unit estimates the actual capacity corresponding to the capacity decay rate and the battery temperature with reference to a capacity estimation lookup table that defines the actual capacity for each capacity decay rate and temperature. The method of claim 1,
The SOC safety margin estimator,
Equation :
SM _upper = RD ^-1 ⅹ 1st correction factor
SM _lower = RD ⅹ 2nd correction factor
Where RD is the resistance decay rate, and the first and second correction coefficients are correction coefficients that mitigate the decrease in the safety margin _upper limit (SM _upper ) and the increase in the safety margin lower limit (SM _lower ). Predefined according to
And estimating the safety margin by calculating the _upper and lower limits SM _upper and SM _lower . The method of claim 7, wherein
The SOC safety margin estimator calculates the first and second correction factors corresponding to the resistance degradation rate by referring to the safety margin lookup table that defines the first and second correction factors for each resistance degradation rate. Estimation device. The method of claim 7, wherein
The SOC safety margin estimator uses a first correction coefficient calculation function and a second correction coefficient calculation function that mathematically define a change pattern of the first and second correction coefficients according to the resistance decay rate obtained through the experiment to determine the resistance decay rate. And calculating a corresponding first and second correction coefficients. The method of claim 1,
The SOC safety margin estimator calculates an upper and lower limit of the safety margin corresponding to the resistance deterioration rate by referring to a safety margin lookup table that defines an upper limit and a lower limit for the safety margin of the state of charge for each resistance degradation rate. Estimation apparatus for a battery capacity, characterized in that for estimating. The method of claim 1,
The usable capacity estimation unit,
Equation :
Usable capacity (Ah) = Actual capacity (Ah) ⅹ (upper safety margin%-lower safety margin%) ⅹ state of charge (%)
Estimating the usable capacity of the battery by means of; The method of claim 1,
The usable capacity estimating unit outputs the estimated usable capacity through the display unit. The method of claim 1,
The usable capacity estimating unit transmits the estimated usable capacity to an external device through a communication interface. The method of claim 1,
A voltage detector, a temperature detector, and a current detector for measuring battery voltage, temperature, and current; And
And a data storage unit which receives data on battery voltage, temperature, and current periodically from the voltage detector, the temperature detector, and the current detector, and stores the data regarding the battery voltage, temperature, and current. The method of claim 1,
And a driveable distance estimator for estimating a driveable distance of the driving apparatus in which the battery is mounted using the estimated usable capacity and the consumption capacity per unit distance. 16. The method of claim 15,
The driving distance estimating unit outputs the estimated driving distance through a display unit. 16. The method of claim 15,
The driving distance estimating unit transmits the estimated driving distance to an external device through a communication interface. An apparatus for estimating usable capacity of a battery according to any one of claims 1 to 17,
A battery coupled with the device,
And a load powered by the battery. The battery management apparatus which mounts the usable capacity estimation apparatus of the battery as described in any one of Claims 1-17 as a PCB circuit or an on-demand semiconductor circuit. A battery comprising a capacity estimation device for a battery according to any one of claims 1 to 17. Estimating a state of charge of the battery;
Estimating the actual capacity of the battery by decreasing the initial capacity of the battery as the resistance degradation rate increases;
Estimating by decreasing the safety margin of the state of charge that can safely use the battery as the resistance degradation rate increases;
Estimating the usable capacity by reflecting a decrease in the estimated safety margin when estimating the available capacity of the battery from the estimated state of charge and the actual capacity; And
And storing the estimated usable capacity. The method of claim 21,
And outputting the estimated usable capacity through a display. The method of claim 21,
And transmitting the estimated available capacity to an external device through a communication interface. The method of claim 21,
Estimating a running distance of the driving apparatus in which the battery is mounted using the estimated usable capacity and consumption capacity per unit distance. 25. The method of claim 24,
And outputting the estimated travelable distance through a display unit. 25. The method of claim 24,
And transmitting the estimated travelable distance to an external device through a communication interface.

Images