KR20190078095A - Battery management system and method for calculating a full charge capacity of a battery - Google Patents

Abstract

Disclosed are a system and a method for managing a battery for calculating a full charge capacity of a battery. According to one embodiment of the present invention, the method comprises the steps of: executing a constant current charging mode for charging the battery to a reference current; periodically calculating a state of charge of the battery based on a terminal voltage and current of the battery in the constant current charging mode; calculating an elapsed time from when the state of charge of the battery reaches a first state of charge to a second state of charge; and calculating a full charge capacity of the battery based on the difference between the elapsed time and the reference time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery management system and method for calculating a full charge capacity of a battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery management system and method for calculating a full charge capacity of a battery, and more particularly, to a battery management system and method for updating a full charge capacity of a battery, .

2. Description of the Related Art In recent years, demand for portable electronic products such as notebook computers, video cameras, and portable telephones has rapidly increased, and electric vehicles, storage batteries for energy storage, robots, and satellites have been developed in earnest. Researches are being actively conducted.

Currently, commercialized batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have little memory effect compared to nickel-based batteries, And is attracting attention because of its high energy density.

The full charge capacity of the battery indicates the amount of charge that can be discharged from the battery when the battery is fully charged. For example, a battery with a full charge capacity of 4000 mAh can supply 4000 mA of current constantly to the load for one hour.

However, since the battery is degraded due to repetitive charging and discharging, the full charge capacity of the battery gradually decreases from the full charge capacity at the time of manufacture of the battery. The full capacity of the battery is one of the parameters necessary for determining the state of charge (SOC) of the battery and the like. Therefore, it is necessary to update the full charge capacity of the battery appropriately to use the battery more safely.

On the other hand, in the conventional art in which the charge accumulation capacity of the battery is updated based on the current accumulation amount while discharging the battery from the full charge state to the full discharge state or the current accumulation amount while charging the battery from the full discharge state to the full charge state, Technology has been disclosed.

However, according to the above conventional technology, the battery has to go through a full discharge state (for example, SOC 0%) and a full charge state (for example, SOC 100% It is not uncommon to be in a full state. Moreover, if the battery is intentionally discharged or fully charged, the battery life may be unnecessarily shortened.

It is an object of the present invention to provide a battery management system and method for updating a full charge capacity of a battery without charging or discharging the battery fully or fully.

Other objects and advantages of the present invention will become apparent from the following description, and it will be understood by those skilled in the art that the present invention is not limited thereto. It is also to be understood that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations thereof.

Various embodiments of the present invention for achieving the above object are as follows.

The method of calculating the full charge capacity of a battery according to an embodiment of the present invention includes: executing a constant current charge mode for charging a battery with a reference current; Calculating a charging state of the battery periodically based on a terminal voltage and a current of the battery in the constant current charging mode; Calculating an elapsed time from when the charged state of the battery reaches the first charged state to when the charged state of the battery reaches the second charged state; And calculating the full charge capacity of the battery based on the elapsed time and the reference time.

The step of periodically calculating the state of charge of the battery may be based on the terminal voltage and current of the battery which is periodically measured.

Calculating the elapsed time includes: detecting a first time when the charged state of the battery reaches the first charged state; Detecting a second time when the charged state of the battery reaches the second charged state; And calculating the elapsed time from the difference between the first time and the second time.

Wherein the step of calculating the full charge capacity of the battery comprises the steps of:

Can be used. In the above equation, FCC _initial is the initial full charge capacity _,? T _elap is the elapsed time _,? T _ref is the reference time, and FCC _new is the full charge capacity.

The method may further include increasing the second state of charge if the elapsed time is less than a predetermined threshold time.

The step of increasing the second state of charge may calculate the amount of increase of the second state of charge based on the ratio of the threshold time to the elapsed time.

The method may further include storing data indicating the full charge capacity in a memory unit.

A battery management system according to another embodiment of the present invention includes: a sensing unit configured to measure a terminal voltage and a current of a battery; And a control unit operatively coupled to the sensing unit. The control unit executes a constant current charging mode for charging the battery with the reference current. In the constant current charging mode, the control unit periodically calculates the charging state of the battery based on the terminal voltage and the current measured by the sensing unit. The control unit calculates the elapsed time from the time when the charging state of the battery becomes the first charging state to the time when the charging state becomes the second charging state. The control unit calculates the full charge capacity of the battery based on the elapsed time and the reference time.

The control unit calculates the following equation:

It is possible to calculate the full charge capacity of the battery. In the above equation, FCC _initial is the initial full charge capacity _,? T _elap is the elapsed time _,? T _ref is the reference time, and FCC _new is the full charge capacity.

The battery pack according to another embodiment of the present invention includes the battery management system.

According to at least one of the embodiments of the present invention, the full charge capacity of the battery can be updated without setting the battery to the full charge state or the full charge state.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a functional block diagram of a battery pack including a battery management system according to an embodiment of the present invention.
2 and 3 are flowcharts illustrating a method of calculating the full charge capacity of a battery according to another embodiment of the present invention.
FIG. 4 is a diagram showing an exemplary timing chart for illustrating an operation of calculating the elapsed time related to the method of FIG. 2; FIG.
5 is a diagram illustrating an exemplary look-up table that is pre-stored in memory for use in determining a reference time associated with the method of FIG.

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

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

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Terms including ordinals, such as first, second, etc., are used for the purpose of distinguishing one of the various components from the rest, and are not used to define components by such terms.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise. In addition, the term " control unit " as described in the specification means a unit for processing at least one function or operation, and may be implemented by hardware or software, or a combination of hardware and software.

In addition, throughout the specification, when a portion is referred to as being "connected" to another portion, it is not necessarily the case that it is "directly connected", but also "indirectly connected" .

1 is a functional block diagram of a battery pack including a battery management system according to an embodiment of the present invention.

Referring to FIG. 1, a battery pack 10 includes a battery 20, a switching unit 30, and a battery management system 100.

The battery 20 includes a positive terminal B + and a negative terminal B-. The battery 20 may include at least one unit cell. When a plurality of unit cells are included in the battery 20, a plurality of unit cells may be electrically connected in series or in parallel. Each unit cell may be, for example, a lithium ion battery, a lithium polymer battery, a nickel cadmium battery, a nickel hydrogen battery, or a nickel zinc battery. Of course, the type of the unit cell is not limited to the above-mentioned kind, and it is not particularly limited as long as it is capable of repeated charge and discharge.

The switching unit 30 is installed in a large current path of the battery pack 10 in order to adjust a current flowing through the battery pack 10, that is, a charging current or a discharging current. The high current path of the battery pack 10 is a path between the positive terminal B + of the battery 20 and the positive terminal P + of the battery pack 10 and the negative terminal B- of the battery 20, And a path between the negative terminal (P < - > 1, a switching unit 30 is provided between a positive terminal P + of a battery pack 10 and a positive terminal B + of a battery 20. However, the installation position of the switching unit 30 is not limited thereto But is not limited thereto. For example, the switching unit 30 may be provided between the negative terminal P- of the battery pack 10 and the negative terminal B- of the battery 20. [

The switching unit 30 may include a charging switch 31 and a discharging switch 32. Each of the charging switch 31 and the discharging switch 32 may comprise a field effect transistor and a parasitic diode, as shown. Each of the charging switch 31 and the discharging switch 32 can be individually turned on or turned off according to the switching signal from the battery management system 100 to thereby adjust the current flowing through the battery 20 .

The battery management system 100 includes a memory unit 110, a sensing unit 120, and a control unit 130, and may further include a communication unit 140. [

The memory unit 110 is not particularly limited as long as it is a storage medium capable of recording and erasing information. For example, the memory unit 110 may be a flash memory type, a hard disk type, a solid state disk type, an SDD type (Silicon Disk Drive type), a multimedia card micro type a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read- a memory, and a storage medium of at least one type. The memory unit 110 may also store a program including various control logic executable by the control unit 130. [ The memory unit 110 may also store data indicating the result of the control logic executed by the control unit 130. [

The sensing unit 120 may include a voltage sensor 121 and a current sensor 122 and may further include a temperature sensor 123. [ Voltage sensor 121, current sensor 122 and temperature sensor, respectively, may be operatively connected to controller 130.

The voltage sensor 121 measures the terminal voltage _Vbat of the battery 20 and transmits a voltage signal representing the measured terminal voltage to the controller 130. [ The terminal voltage corresponds to the potential difference between the positive terminal B + and the negative terminal B-. The control unit 130 stores the measured voltage value indicating the measured terminal voltage in the memory unit 110 based on the voltage signal transmitted from the voltage sensor 121. [

The current sensor 122 measures a current I _bat flowing through the battery 20 and transmits a current signal indicating the measured current to the controller 130. Based on the current signal transmitted from the current sensor 122, the control unit 130 stores in the memory unit 110 a current value indicating the measured current.

The temperature sensor 123 measures the temperature of the battery 20 and transmits a temperature signal indicative of the measured temperature to the control unit 130. The control unit 130 stores the temperature value indicating the measured temperature in the memory unit 110 based on the temperature signal transmitted from the temperature sensor 123. [

The control unit 130 is operatively connected to the memory unit 110, the sensing unit 120, the communication unit 140, and the switching unit 30, and can individually control each operation thereof. The controller 130 may be implemented in hardware as application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs) microprocessors, and other electronic units for performing other functions.

The control unit 130 may control the magnitude of the current supplied to the battery 20 for charging the battery 20 by controlling the duty ratio of the switching signal output to the switching unit 30. [ The control unit 130 can selectively execute the predetermined constant current charging mode for at least a part of the period when the battery pack 10 is connected to the charger. In particular, the control unit 130 may cause a predetermined reference current (e.g., 3A) to flow through the switching unit 30 to the battery 20 while the constant current charging mode is being executed. Accordingly, the battery 20 can be charged with the reference current.

The control unit 130 may periodically calculate the state of charge of the battery using at least one of sensing signals, that is, voltage signals, current signals, and temperature signals periodically transmitted from the sensing unit 120. For example, the control unit 130 updates the charging state of the battery in real time from the terminal voltage, current, and / or temperature measured by the sensing unit 120 by executing a charging state estimation algorithm based on a Kalman filter can do. Various known algorithms including a Kalman filter may be used alone or in combination of two or more to calculate the state of charge of the battery.

The communication unit 140 is configured to support bidirectional communication between the control unit 130 and the external device 1. [

2 and 3 are flowcharts showing a method of calculating a full charge capacity of a battery according to another embodiment of the present invention, and Fig. 4 is a timing chart showing an example timing for explaining an operation of calculating an elapsed time related to the method of Fig. FIG. 5 is a diagram illustrating an exemplary look-up table 500 previously stored in memory for use in determining a reference time associated with the method of FIG.

1 to 5, in step S200, the control unit 130 executes a constant current charging mode for charging the battery 20 with the reference current. The control unit 130, a duty of the switching signal is output to the charge switch 31 is contained in from the constant current charging mode is the time t _S, the battery 20, so that a reference current I _ref is supplied to the switching section 30 The ratio can be adjusted.

In step S210, the control unit 130, and the state of charge of the battery 20 determines whether or not reach the first state of charge SOC _1. The first state of charge SOC ₁ may be fixed or may be changed when the predetermined condition is satisfied. For example, the first state of charge SOC ₁ is initially 30% and may be increased or decreased by the control unit 130. If the result of step S210 is YES, step S220 is performed. If the result of step S210 is "NO ", the process goes back to step S210.

In step S220, the control unit 130 detects a first time t ₁ by the state of charge of the battery 20 reaches the first state of charge SOC _1. The control unit 130, the data representing the detected first time t ₁ can be stored in the memory unit 110. The

In step S230, the control unit 130, and the state of charge of the battery 20 determines whether or not reaching the second state of charge SOC _2. The second state of charge SOC ₂ may be fixed or may be changed if the predetermined condition is satisfied. For example, the second state of charge SOC ₂ is initially 70%, and may be increased or decreased by the controller 130. If the result of step S230 is YES, step S240 is performed. If the result of step S230 is "NO ", the process goes back to step S230.

In step S240, the control unit 130 detects that the state of charge of the battery 20 for the second time t ₂ reaches the second state of charge SOC _2. The control unit 130, the data representing the detected second time t ₂ can be stored in the memory unit 110. The

In step S250, the control unit 130 calculates the elapsed time from when the state of charge of the battery 20 reaches the first state of charge SOC ₁ to when it reaches the second state of charge SOC ₂ . The control unit 130, the difference between the detected first time t ₁ and second time t _2, that is, the second time by subtracting the first time t ₁ at t _2, it is possible to calculate the elapsed time. That is, the elapsed time can be expressed by the following equation (1).

Equation 1: elapsed time = t ₂ - t ₁ =? T _elap

Battery 20 is the more to decrease the full charge capacity of the battery 20 deumeu degeneration, first in the time it takes to charge the battery 20 to the second charge reference current I _ref through from the charge ΔT _elap Will also decrease. That is _,? T _elap contains information on how much the current full charge capacity of the battery 20 has decreased from the initial full charge capacity.

In step S260, the control unit 130 determines whether or not the elapsed time? T _elap is _equal to or greater than a predetermined threshold time. Since the detected first time t ₁ or the second time t ₂ may include an error, the accuracy of the full charge capacity of the battery 20 calculated on the basis of the elapsed time? T _elap not sufficiently large can be lowered. Therefore, if the elapsed time? T _elap is less than the threshold time, an action such as step S270 to be described later is required to increase the elapsed time? T _elap . If the result of step S260 is YES, step S280 is performed. If the result of step S260 is "NO ", the process proceeds to step S270.

In step S270, the controller 130 increases the second charge state. The control unit 130 can calculate the increase amount of the second charge state based on the ratio of the critical time to the elapsed time? T _elap . That is, the increase amount of the second charged state can correspond to the difference between the elapsed time? T _elap and the threshold time. At this time, the controller 130 can calculate the increased second charging state using the following equation (2).

Equation 2:

In Equation (2), SOC _{2 _old} is a previous second charge state, ΔT _th is the threshold time, and SOC 2 - _new is an increased second charge state. If, when the step S270 of the first run, roneun SOC _{2 _old} has previously given initial value can be used. Step S270 is, for example _,? T _elap <? T _{th Lt; th} > / DELTA T _elap &gt; 1. According to Equation _2, SOC 2 _{_old} is 70%, ΔT _th is case 370 seconds, ΔT _elap is 350 seconds, SOC _{2 _new} is large than 74% SOC _{2 _old.}

In step S280, the control unit 130 calculates the full charge capacity of the battery 20 based on the elapsed time? T _elap and the reference time. Referring to FIG. 5, the memory unit 110 may previously store a look-up table 500 in which a one-to-one correspondence relationship between a plurality of SOC changes and a plurality of reference times is defined. Each reference time of the look-up table 500 is the time required to increase the charge state of the battery 20 from the first charge state by the SOC change amount to the reference current I _ref in a state in which the battery 20 is not degenerated And can be determined empirically through preliminary experiments.

The control unit 130 can calculate the SOC change amount using the following equation (3).

Equation 3: ΔSOC = SOC ₂ -SOC ₁

In Equation (3), SOC ₁ is a first charge state, SOC ₂ is a second charge state, and? SOC is an SOC change amount. When proceeding to step S270, the SOC ₂ of Equation (3) may be equal to SOC _{2 _ new} of Equation (2). If in step S270 is not in progress, SOC ₂ of the equation (3) may be equal to the SOC _{2_old} of equation (2).

Then, the control unit 130 can read from the lookup table 500 any one reference time corresponding to the calculated SOC change amount? SOC. For example, referring to FIG. 5, if the calculated SOC change amount SOC is 44%, 440 seconds can be read from the look-up table 500 as a reference time to be used for updating the full charge capacity.

The difference between the full charge capacity of the battery 20 and the initial full charge capacity may correspond to the ratio of the elapsed time? T _elap with respect to the reference time. The controller 130 can update the full charge capacity of the battery 20 using the following equation (4).

Equation 4:

In Equation (4), FCC _initial is the initial full charge capacity of the battery 20,? T _ref is the reference time corresponding to? SOC, and FCC _new is the updated full charge capacity. The initial full charge capacity FCC _initial represents the maximum amount of charge that can be stored in the battery 20 at the beginning of life (BOL) at which the battery 20 is not degenerated. The data indicating the initial full charge capacity FCC _initial may be stored in the memory unit 110 in advance.

In step S290, the control unit 130 stops the constant current charging mode. Accordingly, at the time t _E From the basic supply of the current I _ref on the battery 20 it is cut off or may reference current I _ref, which is different from current can be caused to flow through the battery (20). Alternatively or additionally, the control unit 130 may store the data indicating the updated full charge capacity FCC _new in the memory unit 110 or may transmit the data to the external device 1 through the communication unit 140.

During the period from the start of the constant current charging mode by the step S200 to the stop of the constant current charging mode by the step S290, the control unit 130 controls the terminal voltage and the current of the battery periodically measured by the sensing unit 120 The charging state of the battery 20 is periodically calculated. While the constant current charging mode is being executed, the current measured by the sensing unit 120 will have a very small difference that is equal to or negligible as the reference current. As described above, the state of charge of the battery can be calculated using various known algorithms such as a Kalman filter and the like.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative, The present invention is not limited to the drawings, but all or some of the embodiments may be selectively combined so that various modifications may be made.

10: Battery pack
20: Battery
30:
100: Battery management system
110: Memory
120: sensing unit
130:
140:

Claims (10)

Executing a constant current charging mode for charging the battery with a reference current;
Calculating a charging state of the battery periodically based on a terminal voltage and a current of the battery in the constant current charging mode;
Calculating an elapsed time from when the charged state of the battery reaches the first charged state to when the charged state of the battery reaches the second charged state; And
Calculating a full charge capacity of the battery based on the elapsed time and the reference time;
And determining the full charge capacity of the battery.
The method according to claim 1,
The step of periodically calculating the state of charge of the battery includes:
A method for calculating the full charge capacity of a battery based on terminal voltage and current of the battery periodically measured.
The method according to claim 1,
Wherein the calculating the elapsed time comprises:
Detecting a first time when the charged state of the battery reaches the first charged state;
Detecting a second time when the charged state of the battery reaches the second charged state; And
Calculating the elapsed time from a difference between the first time and the second time;
And determining the full charge capacity of the battery.
The method according to claim 1,
The step of calculating the full charge capacity of the battery includes:
The following equation:

_Wherein FCC _initial is an initial full charge capacity, DELTA T _elap is the elapsed time, DELTA T _ref is the reference time, and FCC _new is the full charge capacity.
The method according to claim 1,
Increasing the second charge state if the elapsed time is less than a predetermined threshold time;
Further comprising the step of calculating the full charge capacity of the battery.
6. The method of claim 5,
Wherein increasing the second charge state comprises:
Calculating an increase amount of the second charge state based on a ratio of the critical time to the elapsed time.
The method according to claim 1,
Storing data indicating the full charge capacity in a memory unit;
Further comprising the step of calculating the full charge capacity of the battery.
A sensing unit configured to measure a terminal voltage and a current of the battery; And
And a control unit operatively coupled to the sensing unit,
Wherein,
A constant current charging mode for charging the battery with a reference current,
Wherein in the constant current charging mode, the charging state of the battery is periodically calculated based on the terminal voltage and the current measured by the sensing unit,
Calculating an elapsed time from when the charged state of the battery becomes the first charged state to when the charged state becomes the second charged state,
And calculates the full charge capacity of the battery based on the elapsed time and the reference time.
9. The method of claim 8,
Wherein,
The following equation:

_{Wherein the} FCC _initial is an initial full charge capacity _,? T _elap is the elapsed time _,? T _ref is the reference time, and FCC _new is the full charge capacity.
A battery management system according to any one of claims 8 to 9,
And a battery pack.

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