KR102446796B1 - Apparatus and method for controlling electric current for a battery pack - Google Patents

Abstract

A current control apparatus and method for a battery pack are provided. A current control device according to an embodiment of the present invention is a current sensor configured to measure a current flowing through the current path of a plurality of switching circuits interconnected in parallel between a first node and a second node of the current path of the battery pack and a control unit operatively coupled to each of the switching circuits and the current sensor. The controller determines a reference current based on the measured current. The control unit calculates the target number based on the reference current. The control unit selects the same number of the switching circuits as the target number from among the plurality of switching circuits. The control unit outputs a switching signal for switching each of the selected switching circuits to a turn-on state.

Description

Apparatus and method for controlling electric current for a battery pack

The present invention relates to an apparatus and method for controlling a current for a battery pack, and more particularly, to an apparatus and method for controlling the magnitude of a current flowing through a current path of a battery pack during charging and discharging of the battery pack. .

Recently, as the demand for portable electronic products such as laptops, video cameras, and portable telephones is rapidly increasing, and development of electric vehicles, energy storage batteries, robots, satellites, etc. is in full swing, high-performance batteries that can be repeatedly charged and discharged have been developed. Research is actively underway.

Currently, commercially available batteries include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium batteries. It is attracting attention due to its low energy density and high energy density.

A mechanical relay for regulating the current flowing through the battery pack is usually installed in the current path between the battery pack and the load. The mechanical relay is turned on or turned off by physically moving a contact according to a control signal. Therefore, whenever the mechanical relay is changed from the turn-on state to the turn-off state or from the turn-off state to the turn-on state, a noise is generated from the contact, causing inconvenience to the user.

In addition, the mechanical relay may be switched to an undesired state by an impact from the outside. For example, when a vehicle crash occurs, the mechanical relay may be unintentionally switched from a turned-off state to a turned-on state. This may act as a great risk factor for users.

The present invention has been devised to solve the above problems, and an object of the present invention is to provide a current control device including a plurality of switching circuits replacing a mechanical relay, and a method for controlling the same.

Other objects and advantages of the present invention may be understood by the following description, and will become more clearly understood by the examples of the present invention. In addition, it will be readily apparent that the objects and advantages of the present invention can be realized by means and combinations thereof indicated in the claims.

A current control apparatus for a battery pack according to an aspect of the present invention includes: a plurality of switching circuits interconnected in parallel between a first node and a second node of a current path of the battery pack; a current sensor configured to measure a current flowing through the current path; and a control unit operatively coupled to each of the switching circuits and the current sensor. The controller determines a reference current based on the measured current. The control unit calculates the target number based on the reference current. The control unit selects the same number of the switching circuits as the target number from among the plurality of switching circuits. The control unit outputs a switching signal for switching each of the selected switching circuits to a turn-on state.

Each of the switching circuits may include a charging MOSFET and a discharging MOSFET connected in series between the first node and the second node.

The controller may determine the reference current based on a change trend of the current measured by the current sensor during the past observation period.

The controller may determine a maximum value of the current measured by the current sensor during the observation period as the reference current. The reference current may be less than or equal to a predetermined threshold current.

The control unit may calculate a degree of deterioration of each of the switching circuits based on a cumulative use period of each of the switching circuits. The accumulated use period is an accumulated amount of time each of the switching circuits has operated in a turned-on state until now.

The control unit may calculate the degree of deterioration of each of the switching circuits further based on the accumulated current amount of each of the switching circuits. The accumulated current amount is an accumulated amount of current flowing through each of the switching circuits up to now.

The target number of the switching circuits in the order of decreasing the degree of deterioration among the plurality of switching circuits may be switched to the turn-on state by the switching signal.

A battery pack according to another aspect of the present invention includes the current control device.

A current control method for a battery pack according to another aspect of the present invention comprises the steps of: receiving, by a control unit operatively coupled to a current sensor, a current signal representing a current of the battery pack measured by the current sensor; determining, by the controller, a reference current based on the measured current; calculating, by the controller, a target number based on the reference current; selecting, by the control unit, the same number of the switching circuits as the target number from among a plurality of switching circuits; and outputting, by the control unit, a switching signal for switching each of the selected switching circuits to a turn-on state.

The reference current may be determined based on a maximum value of a current measured by the current sensor during a past observation period.

The method may further include calculating, by the control unit, the degree of deterioration of each of the switching circuits based on the cumulative use period of each of the switching circuits. The accumulated use period is an accumulated amount of time each of the switching circuits has operated in a turned-on state until now.

The target number of the switching circuits in the order of decreasing the degree of deterioration among the plurality of switching circuits may be switched to the turn-on state by the switching signal.

According to at least one of the embodiments of the present invention, it is possible to replace the mechanical relay using a plurality of switching circuits. Accordingly, it is possible to solve the disadvantages of the mechanical relay, such as noise.

In addition, according to at least one of the embodiments of the present invention, by selectively controlling each switching circuit according to the degree of deterioration of each of the plurality of switching circuits, a situation in which some of the plurality of switching circuits are used excessively than the others is prevented can do.

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

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the detailed description of the present invention to be described later, so the present invention is described in such drawings should not be construed as being limited only to
1 is a diagram exemplarily showing the configuration of a battery pack according to an embodiment of the present invention.
FIG. 2 is a diagram exemplarily illustrating the switching circuit shown in FIG. 1 .
3 is a diagram illustrating the switching circuit shown in FIG. 1 as an equivalent resistance.
4 is a flowchart illustrating a current control method for a battery pack according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the configuration shown in the embodiments and drawings described in the present specification is merely the most preferred embodiment of the present invention and does not represent all of the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

In addition, in the description of the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms including an ordinal number such as 1st, 2nd, etc. are used for the purpose of distinguishing any one of various components from the others, and are not used to limit the components by such terms.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, a term such as <control unit> described in the specification means a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

In addition, throughout the specification, when a part is "connected" with another part, it is not only "directly connected" but also "indirectly connected" with another element interposed therebetween. include

1 is a diagram exemplarily showing the configuration of a battery pack according to an embodiment of the present invention, FIG. 2 is a diagram exemplarily showing the switching circuit shown in FIG. 1, and FIG. 3 is the switching shown in FIG. A diagram showing the circuit as an equivalent resistance.

Referring to FIG. 1 , a battery pack 10 includes a battery module 20 and a current control device 100 .

The battery module 20 includes at least one battery cell. Each battery cell may be, for example, a lithium ion battery. Of course, the type of the battery cell is not limited to the lithium ion battery, and is not particularly limited as long as it can be repeatedly charged and discharged. Each battery cell included in the battery module 20 is electrically connected to other battery cells in series or in parallel.

The current control device 100 includes a current sensor 120 , a plurality of switching circuits SC, and a controller 130 .

The current sensor 120 is installed on the high voltage line HL or the low voltage line LL, which is a current path of the battery pack 10 . The current sensor 120 is configured to measure the current flowing through the current path. The current sensor 120 outputs a current signal representing the measured current to the controller 130 .

The plurality of switching circuits SC are electrically connected between the first node N1 and the second node N2 of the current path. The plurality of switching circuits SC are electrically connected in parallel to each other. For convenience of description, it is assumed that the current control device 100 includes five switching circuits SC1 to SC5 as shown in FIG. 1 . Of course, it should be understood that less than five or more than six switching circuits SC may be included in the current control device 100 . The plurality of switching circuits SC1 to SC5 may be sequentially disposed at different physical locations, as shown in FIG. 1 .

Referring to FIG. 2 , each switching circuit SC may include a charging MOSFET FC and a discharging MOSFET FD. The charging MOSFET FC and the discharging MOSFET FD included in each switching circuit SC are connected in series between the first node N1 and the second node N2 .

The charging MOSFET FC includes a source, a drain, a gate, and a parasitic diode. When a voltage equal to or greater than the threshold voltage is applied to the gate of the charging MOSFET FC, the charging MOSFET FC is switched from the turned-off state to the turn-on state. The charging MOSFET FC has a first on-resistance R1.

The discharge MOSFET FD includes a source, a drain, a gate, and a parasitic diode. When a voltage equal to or greater than the threshold voltage is applied to the gate of the discharge MOSFET FD, the discharge MOSFET FD is switched from the turned-off state to the turn-on state. The discharge MOSFET FD has a second on-resistance R2. The on-resistance is the internal resistance between the source and drain of the MOSFET in the turned-on state. Referring to FIG. 3 , when both the charging MOSFET FC and the discharging MOSFET FD of the switching circuit SC are turned on, the switching circuit SC has a first on-resistance R1 and a second resistor R2 ) can be treated as a resistor with an equivalent resistance equal to the sum of

The parasitic diode of the charging MOSFET FC and the parasitic diode of the discharging MOSFET FD are connected in opposite directions. That is, the anode of the parasitic diode of the charging MOSFET FC is connected to the anode of the parasitic diode of the discharging MOSFET FD, or the cathode of the parasitic diode of the charging MOSFET FC is connected to the cathode of the parasitic diode of the discharging MOSFET FD. can Accordingly, while both the charging MOSFET FC and the discharging MOSFET FD have the turned-off state, the flow of current through the current path is blocked.

The gate of the charging MOSFET FC and the gate of the discharging MOSFET FD included in each switching circuit SC are electrically connected to each other through the common node CN. Accordingly, when the controller 130 outputs a switching signal (eg, 3Vdc) to the common node CN, the switching signal is applied to both the gate of the charging MOSFET FC and the gate of the discharging MOSFET FD. The switching signal output by the controller 130 may be a signal having a voltage equal to or greater than a threshold voltage.

The controller 130 is operatively coupled to the current sensor 120 and the plurality of switching circuits SC1 to SC5. A memory device may be embedded in the controller 130 , and as the memory device, for example, a RAM, ROM, register, hard disk, optical recording medium, or magnetic recording medium may be used. The memory device may store, update, and/or erase a program including various control logic executed by the controller 130 and/or data generated when the control logic is executed.

The control unit 130 is configured to selectively turn on/off the plurality of switching circuits SC1 to SC5. Specifically, the controller 130 is electrically connected to the plurality of switching circuits SC1 to SC5 through the plurality of wires SL1 to SL5 . The controller 130 may output the switching signal to only some of the plurality of switching circuits SC1 to SC5 and may not output the switching signal to the other switching circuits SC. Accordingly, only some of the plurality of switching circuits SC1 to SC5 may operate in a turned-on state, and the remaining switching circuits SC may operate in a turned-off state. Of course, the controller 130 may output a switching signal to all of the plurality of switching circuits SC1 to SC5 .

The controller 130 may periodically determine a reference current based on a current signal periodically transmitted from the current sensor 120 . The controller 130 may calculate a reference current based on a change trend of a current measured by the current sensor 120 during an observation period in the past based on the current time point. For example, the controller 130 may determine the maximum value of the current measured multiple times by the current sensor 120 during the observation period as the reference current. A period in which the reference current is determined may be the same as a period in which the current is measured by the current sensor 120 .

Power P consumed between the first node N1 and the second node N2 during charging or discharging of the battery pack 10 is the current I flowing through the first node N1 and the second node N2 is proportional to the square of , and inversely proportional to the resistance R between the first node N1 and the second node N2. That is, P = I ² R.

As the power consumption P increases, the amount of heat is increased, and when the amount of heat is greater than a certain level, there is a risk of damage to each of the switching circuits SC. Therefore, by adjusting the resistance R based on the current I, it is required to keep the power consumption P below the predetermined maximum power P _max . The resistance R is determined by the switching circuit SC in the turned-on state among the plurality of switching circuits SC1 to SC5.

The controller 130 may calculate the target number based on the reference current. The target number is the number of switching circuits SC to be switched to the turn-on state among the plurality of switching circuits SC1 to SC5. When n of the plurality of switching circuits SC1 to SC5 are turned on, the resistance R becomes 3/n milliohm according to the low sum synthesis principle.

For better understanding, the maximum power P _max is 60 W, the threshold current representing the predetermined maximum allowable current of the battery pack 10 is 300 A, and the equivalent resistance is 3 milliohms [ mili-ohm].

If the reference current is 300A, the resistance R must be less than or equal to 60/(300×300) ohms, so that the power consumption P becomes less than or equal to the maximum power P _max . Since the resistance R becomes 60/(300×300) ohms or less only when at least five switching circuits SC are turned on, the controller 130 calculates 5 as the target number.

If the reference current is 270A, the resistance R must be 60/(270×270) ohms or less, so that the power consumption P becomes less than or equal to the maximum power P _max . Since the resistance R becomes 60/(270×270) ohms or less only when at least four switching circuits SC are turned on, the controller 130 calculates 4 as the target number.

If the reference current is 240A, the resistance R must be 60/(240×240) ohms or less, so that the power consumption P becomes the maximum power P _max or less. Since the resistance R becomes 60/(240×240) ohms or less only when at least three switching circuits SC are turned on, the controller 130 calculates 3 as the target number.

If the reference current is 200A, the resistance R must be 60/(200×200) ohms = 1.5 milliohms or less, so that the power consumption P becomes the maximum power P _max or less. Since the resistance R becomes 1.5 milliohms or less only when the at least two switching circuits SC are turned on, the controller 130 calculates 2 as the target number.

If the reference current is 150A, the resistance R must be 60/(150×150) ohms or less, so that the power consumption P becomes the maximum power P _max or less. Since the resistance R becomes 60/(150×50) ohms or less only when at least one switching circuit SC is turned on, the controller 130 calculates 1 as the target number.

When the target number is calculated, the control unit 130 randomly selects the same number of switching circuits SC as the target number among the plurality of switching circuits SC1 to SC5, and then turns on each selected switching circuit SC. Outputs a switching signal for switching. For example, when the target number is 3, the controller 130 outputs a switching signal to the switching circuit SC1, the switching circuit SC2, and the switching circuit SC3, and to the switching circuit SC4 and the switching circuit SC5 The switching signal may not be output.

Alternatively, the controller 130 may output a switching signal to the target number of the switching circuits SC in the order of decreasing the degree of degradation among the plurality of switching circuits SC1 to SC5 . To this end, the controller 130 may periodically determine the degree of deterioration of each switching circuit SC.

The controller 130 may calculate the degree of deterioration of each switching circuit SC based on the accumulated use period of each switching circuit SC. The cumulative use period is the accumulated amount of time each switching circuit SC operates in the turned-on state from the time it is mounted in the battery pack 10 to the present.

The controller 130 may calculate the degree of deterioration of each switching circuit SC further based on the accumulated current amount of each switching circuit SC. The accumulated current amount is the accumulated amount of the current flowing through each switching circuit SC to the present.

The controller 130 may calculate the degree of degradation of the switching circuits SCi,i=1 to 5 by using Equation 1 below.

<Equation 1>

DD _i = (α×A _i ) + (β×B _i )

In Equation 1, α is a first weight of a predetermined amount, β is a second weight of a predetermined amount, A _i is the accumulated use period of the switching circuit SCi, B _i is the accumulated current amount of the switching circuit SCi, DD _i is the deterioration degree of the switching circuit SCi.

For example, if the target number is 3 and DD ₁ < DD ₃ < DD ₄ < DD ₂ = DD ₅ , the controller 130 switches the switching circuit SC1 , the switching circuit SC3 , and the switching circuit SC4 to the switching circuit SC4 . signal can be output.

As another example, when the target number is 4 and DD ₁ < DD ₂ = DD ₃ < DD ₄ = DD ₅ , the controller 130 may include the switching circuit SC1 , the switching circuit SC2 , the switching circuit SC3 and the switching circuit The switching signal may be output to SC4 , but instead the switching signal may be output to the switching circuit SC1 , the switching circuit SC2 , the switching circuit SC3 , and the switching circuit SC5 . The reason is that the switching circuit SC5 may be more advantageous in heat dissipation than the switching circuit SC4 because the distance from the switching circuits SC1 , SC2 , and SC3 is greater.

As another example, if the target number is 2 and DD ₁ = DD ₂ = DD ₃ = DD ₄ = DD ₅ , the controller 130 sends a switching signal to the switching circuit SC1 and the switching circuit SC5 that are farthest from each other. can be printed out. Of course, the controller 130 may output a switching signal from the plurality of switching circuits SC1 to SC5 to any one of the remaining nine pairs that can be combined.

4 is a flowchart illustrating a current control method for the battery pack 10 according to another embodiment of the present invention.

1 to 4 , in step 400 , the controller 130 receives a current signal representing the current of the battery pack 10 periodically measured by the current sensor 120 during the observation period.

In step 410, the controller 130 determines a reference current based on the current periodically measured during the observation period.

In step 420 , the controller 130 calculates the target number based on the reference current.

In step 430 , the controller 130 selects the same number of switching circuits SC as the target number from among the plurality of switching circuits SC1 to SC5 .

In step 440 , the controller 130 outputs a switching signal for switching each of the selected switching circuits SC to a turn-on state.

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

In the above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto and will be described below with the technical idea of the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims.

In addition, since the present invention described above is capable of various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention for those of ordinary skill in the art to which the present invention pertains, the above-described embodiments and attachments It is not limited by the drawings, and all or part of each embodiment may be selectively combined so that various modifications may be made.

10: battery pack
20: battery module
100: current control device
SC: switching circuit
120: current sensor
130: control unit

Claims (13)

A current control device for a battery pack, comprising:
a plurality of switching circuits interconnected in parallel between a first node and a second node of a current path of the battery pack;
a current sensor configured to measure a current flowing through the current path; and
a control unit operatively coupled to each of the switching circuits and the current sensor;
The control unit is
Based on the measured current, determine a reference current,
Calculate the target number based on the reference current,
selecting the same number of the switching circuits as the target number in the order of decreasing the degree of degradation among the plurality of switching circuits;
and output a switching signal for switching each of the selected switching circuits into a turned-on state.
According to claim 1,
Each of the switching circuits,
and a charging MOSFET and a discharging MOSFET connected in series between the first node and the second node.
According to claim 1,
The control unit is
and determining the reference current based on a change trend of the current measured by the current sensor during a past observation period.
4. The method of claim 3,
The control unit is
and determining a maximum value of the current measured by the current sensor during the observation period as the reference current.
According to claim 1,
The reference current is
A current control device that is below a predetermined threshold current.
According to claim 1,
The control unit is
Calculating the degree of deterioration of each of the switching circuits based on the cumulative usage period of each of the switching circuits,
and the accumulated use period is an accumulated amount of time during which each of the switching circuits has operated in a turned-on state until now.
7. The method of claim 6,
The control unit is
Calculating the degree of deterioration of each of the switching circuits further based on the accumulated current amount of each of the switching circuits,
The accumulated current amount is an accumulated amount of current flowing through each of the switching circuits until now.
delete A current control device according to any one of claims 1 to 7;
A battery pack comprising a.
In the current control method for a battery pack,
receiving, by a control unit operatively coupled to a current sensor, a current signal indicative of a current in the battery pack measured by the current sensor;
determining, by the controller, a reference current based on the measured current;
calculating, by the controller, a target number based on the reference current;
selecting, by the control unit, the same number of the switching circuits as the target number in the order of decreasing the degree of deterioration from among the plurality of switching circuits; and
outputting, by the control unit, a switching signal for switching each of the selected switching circuits to a turn-on state;
Including, a current control method.
11. The method of claim 10,
The reference current is
based on the maximum value of the current measured by the current sensor during a past observation period.
11. The method of claim 10,
calculating, by the control unit, a degree of deterioration of each of the switching circuits based on the cumulative use period of each of the switching circuits;
further comprising,
The accumulated use period is an accumulated amount of a time in which each of the switching circuits has operated in a turned-on state until now.
delete

Images