KR20180119320A - Apparatus and method for preventing overcharge - Google Patents

Abstract

The present invention provides a device and a method for protecting each of a plurality of cell stacks included in a battery pack from overcharging. According to an embodiment of the present invention, the device for preventing overcharging comprises: a voltage measuring part measuring voltage of each cell stack, and generating a first monitoring signal representing the measured voltage; a bypass part having a plurality of bypass circuits composed to selectively provide a bypass path to each cell stack; and a controller communicably connected to the voltage measuring part and the bypass part. Each bypass circuit includes: a bypass switch; and a plurality of current limit circuits connected in parallel to each cell stack through the bypass switch. The controller controls each bypass switch based on the first monitoring signal from the voltage measuring part.

Description

[0001] APPARATUS AND METHOD FOR PREVENTING OVERCHARGE [0002]

More particularly, the present invention relates to an apparatus and a method for protecting each of a plurality of cell stacks included in a battery pack from overcharging.

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.

BACKGROUND ART [0002] Battery packs mounted on electric vehicles or the like generally include a plurality of cell stacks connected in series or in parallel with each other. At this time, each cell stack includes one or two or more battery cells connected in series with each other.

The state of each cell stack included in such a battery pack is monitored by a controller equipped with a battery management system (BMS). The controller can output a signal for controlling the balancing operation, the cooling operation, the charging operation, the discharging operation, and the like based on the monitored state from each cell stack.

As the charging current is supplied to the battery pack, the voltage of each cell stack gradually rises and can be overcharged. There is a possibility that a dangerous situation such as explosion of the cell stack may occur due to overcharging. As a prior art for preventing such overcharging, Patent Document 1 exists. The battery pack according to Patent Document 1 includes a battery and a current cutoff device corresponding to the cell stack. When an overvoltage occurs in the battery, the current cutoff device electrically separates the battery from the high current path.

However, when the battery is simply overheated and the battery is electrically disconnected from the large current path, a major problem may arise. For example, there is a risk that the electric vehicle suddenly stops when the battery of the battery pack mounted in the electric vehicle is electrically disconnected from the high current path.

Patent Document 1: Korean Patent Laid-Open Publication No. 10-2014-0017043 (public date: February 11, 2014)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a battery pack having a structure in which, when some cell stacks included in a battery pack are overcharged, And an object of the present invention is to provide an apparatus and a method.

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.

An overcharge preventing device according to one aspect of the present invention is for preventing overcharging of a plurality of cell stacks connected in series in a large current path. The overcharge protection device may further include: a voltage measurement unit that measures a voltage of each of the cell stacks and generates a first monitoring signal indicating the measured voltage; A bypass unit having a plurality of bypass circuits configured to selectively provide a bypass path to each cell stack; And a controller communicably connected to the voltage measuring unit and the bypass unit. Each bypass circuit includes a bypass switch; And a plurality of current limiting circuits connected in parallel to the respective cell stacks via the bypass switch. The controller controls each of the bypass switches based on a first monitoring signal from the voltage measuring unit.

In addition, each of the current limiting circuits may include one or two or more resistors connected in series with each other.

In addition, any one of the plurality of current limit circuits may be spaced apart from the rest by a predetermined distance.

The voltage measuring unit may include a plurality of voltage sensors connected in parallel to the respective cell stacks.

The cell stack may further include a disconnecting unit electrically disconnectable from the large current path.

Further, the disconnecting unit may include: a fuse in which each cell stack and each of the plurality of current limiting circuits are serially connected to each cell stack between two nodes connected in parallel; And a plurality of protection elements each having an end connected to the fuse; And a plurality of disconnect switches each having one end connected to the other end of each of the heat generating resistors and the other end connected to an electrode of each of the cell stacks.

In addition, the controller can determine whether or not each cell stack is overcharged based on the first monitoring signal.

Further, the controller may control the disconnecting unit to electrically disconnect each cell stack determined to be overcharged from the high current path.

Further, the controller may update the overcharge count of each cell stack each time the cell stack is determined to be overcharged.

In addition, the controller may control each of the disconnecting switches connected in series to each cell stack in which the number of times of overcharge reaches a predetermined threshold number, to be in the ON state.

And a plurality of capacitors connected in parallel to the respective bypass circuits, respectively.

According to another aspect of the present invention, there is provided a battery pack comprising: the overcharge protection device; And a plurality of cell stacks connected in series in the large current path. The overcharge protection device performs an overcharge prevention operation for each of the cell stacks.

According to embodiments of the present invention, when some of the cell stacks included in the battery pack are overcharged, at least a part of the charging current may be supplied to the remaining cell stack by bypassing the overcharged cell stack. Therefore, even if some of the cell stacks reach the overcharge state, the remaining cell stacks that are not overcharged can be charged.

Further, among the plurality of cell stacks included in the battery pack, the cell stack which is frequently overcharged more frequently than a certain frequency can be electrically separated from the high current path. At this time, instead of each cell stack electrically separated from the large current path, a bypass path constituting a large current path is provided in the battery pack. Therefore, even if some of the cell stacks are electrically disconnected from the large current path, the remaining cell stacks that are not overcharged can be charged and discharged.

Further, it is possible to provide a discharge path to each cell stack electrically isolated from the large current path. Thus, the discharge of each cell stack electrically isolated from the large current path and the charging of each cell stack electrically connected to the large current path can proceed together.

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 schematic view illustrating a battery pack according to an embodiment of the present invention.
2 is a schematic configuration diagram of a circuit corresponding to the battery pack shown in Fig.
FIG. 3 is a view showing an embodiment of the protective device shown in FIG. 2. FIG.
4 is a circuit diagram showing a circuit corresponding to the current limiting block shown in FIG. 2. FIG.
FIGS. 5 and 6 are diagrams showing two implementations of the current limiting block shown in FIG.
7 to 9 are diagrams referred to in describing the operation of the circuit shown in Fig.
10 is a flowchart showing an overcharge prevention method 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, 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 part is referred to as being "connected" to another part, it is not limited to a case where it is directly connected to the other part, .

1 is a view showing a schematic configuration of a battery pack 1 according to an embodiment of the present invention.

Referring to FIG. 1, a battery pack 1 includes a battery module 10 and an overcharge protection device 100. The battery module 10 includes n cell stacks 20. Here, n is a natural number of 1 or more. The overcharge protection device 100 basically includes a voltage measurement unit 110, a bypass unit 120 and a controller 170 and selectively supplies the isolation unit 140, the smoothing unit 150, 160, < / RTI >

The plurality of cell stacks 20-1 to 20-n are connected in series to each other and are provided on the large current path of the battery pack 1. [ In detail, each cell stack 20 can be connected between two adjacent nodes among a plurality of nodes N1 to N4 sequentially located in a large current path. For example, the anode and cathode of the second cell stack 20-2 may be connected between the two nodes N2 and N3.

The voltage measuring unit 110 measures the voltage of each cell stack 20 and generates a first monitoring signal indicating the measured voltage. The first monitoring signal generated by the voltage measuring unit 110 is transmitted to the controller 170.

The bypass portion 120 is configured to selectively provide at least one bypass path that constitutes a large current path together with or in place of each cell stack 20. That is, the bypass unit 120 may provide a bypass path only to a part of the cell stacks 20 and not provide a bypass path to the remaining cell stacks 20.

Some or all of the charge current flows through each bypass path. Therefore, while the charging current is supplied to the battery pack 1, the charging of the cell stack 20 provided with the bypass path is stopped or proceeded slowly.

The disconnecting unit 140 is configured so that each cell stack 20 can be electrically disconnected from the battery pack 1. That is, the disconnecting unit 140 electrically or temporarily disconnects each stack 20 from the large current path. The controller 170 can operate the bypass unit 120 and the disconnecting unit 140 in conjunction with each other. For example, when the cell stack 20 is disconnected from the high current path by the disconnecting unit 140 or a predetermined time (for example, several milliseconds) elapses after the cell stack 20 is disconnected, the bypass unit 120 is disconnected It is possible to provide the bypass path only to the cell stack 20. Each bypass path provided to the separate cell stack 20 constitutes a large current path in place of the separated cell stack 20. The fact that the cell stack 20 is electrically removed / disconnected from the large current path may mean that the cell stack 20 becomes in a state where it can not receive the charging current through the large current path.

The smoothing unit 150 is configured to suppress a sharp voltage drop occurring in a part of the large current path when each cell stack 20 is removed from the large current path by the disconnecting unit 140. [

The current measuring unit 160 measures a charging current supplied to each cell stack 20 and generates a second monitoring signal indicating the measured charging current. The second monitoring signal generated by the current measuring unit 160 is transmitted to the controller 170. The current measuring unit 160 includes a shunt resistor provided in a large current path, and can measure the charging current from the voltage generated in the shunt resistor by the charging current.

Controller 170 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 controller 170 is communicably connected to the voltage measuring unit 110, the bypass unit 120, the disconnecting unit 140, and / or the current measuring unit 160 to control their operation as a whole. Here, the fact that two different components are communicatively connected means that one component is connected through wired and / or wireless so as to transmit signals or data to another component. The voltage measuring unit 110 described above can be incorporated in the controller 170. [

Controller 170 is configured to perform an overcharge protection operation for each cell stack 20. [ In particular, the controller 170 controls the bypass unit 120 and / or the disconnecting unit 140 based on the first monitoring signal from the voltage measuring unit 110. According to the control signal from the controller 170, the disconnecting unit 140 can electrically isolate each cell stack 20 from the large current path. Also, in accordance with a control signal from the controller 170, the bypass unit 120 may provide a bypass path to each cell stack 20, or may block the provided bypass path.

Hereinafter, for the sake of understanding, it is assumed that three cell stacks 20-1 to 20-3 connected in series to each other are included in the battery pack 1.

2 is a schematic configuration diagram of a circuit corresponding to the battery pack 1 shown in Fig. The plurality of cell stacks 20 included in the battery pack 1 are installed in a large current path between the two power terminals (+, -) of the battery pack 1.

Referring to FIGS. 1 and 2, each cell stack 20 includes at least one battery cell 21. When a plurality of battery cells 21 are included in each cell stack 20, any one of them may be connected in series or in parallel with at least one of the others. In addition, each cell stack 20 may include a case 22 having a structure at least partially covering each battery cell 21 included therein. The case 22 may be made of a metal material for efficient heat dissipation.

The voltage measuring unit 110 may include a plurality of voltage sensors 111. The number of voltage sensors 111 may be the same as the number of cell stacks 20. In this case, the voltage sensor 111 may be provided for each cell stack 20. That is, the voltage sensor 111 can correspond to the cell stack 20 on a one-to-one basis.

Each voltage sensor 111 is connected to each cell stack 20 in parallel. That is, each of the first voltage sensor 111-1, the second voltage sensor 111-2 and the third voltage sensor 111-3 includes a first cell stack 20-1, a second cell stack 20-1, -2) and the third cell stack 20-3. Each voltage sensor 111 measures the voltage of a cell stack 20 connected in parallel thereto. The first monitoring signals S1-1 to S1-3 indicating the voltages of the respective cell stacks 20 measured by the plurality of voltage sensors 111 are transmitted to the controller 170. [

 The bypass unit 120 includes at least one bypass circuit 130. Preferably, the number of the bypass circuits 130 included in the bypass unit 120 may be equal to the number of the cell stacks 20. In this case, one bypass circuit 130 may be provided for each cell stack 20. That is, the bypass circuit 130 and the cell stack 20 can correspond one to one.

Each bypass circuit 130 includes a bypass switch 131 and a current limiting block B and is configured to selectively provide a bypass path to each cell stack 20. That is, each bypass circuit 130 provides a bypass path to the cell stack 20 connected in parallel at the time of activation, and when it is inactivated, the bypass path corresponding to each cell stack 20 connected in parallel . Here, activation of the bypass circuit 130 may mean that the bypass switch 131 included in the bypass circuit 130 is controlled to be in the ON state.

When the bypass path is provided to at least one cell stack 20, the magnitude of the charge current flowing through each bypass path can be determined by the resistance value of the current limiting block B constituting each bypass path . For example, when the voltage between the positive terminal (+) and the negative terminal (-) of the battery pack 1 is constant, the larger the resistance value of the current limiting block B constituting each bypass path, Loses.

Each bypass circuit 130 may be connected in parallel to each cell stack 20 via two adjacent nodes on the large current path. That is, each of the first bypass circuit 130-1, the second bypass circuit 130-2, and the third bypass circuit 130-3 includes a first cell stack 20-1, And may be connected in parallel to the stack 20-2 and the third cell stack 20-3.

When at least one of the plurality of bypass circuits 130-1 to 130-3 is activated by the controller 170, the activated bypass circuit 130 bypasses the cell stack 20 connected thereto in parallel, Provide a path.

The disconnecting unit 140 includes a plurality of disconnecting circuits. Each disconnect circuit includes a disconnect switch 141 and a protection element 142. The number of disconnecting circuits included in the disconnecting unit 140 may be the same as the number of the cell stacks 20. [ In this case, one disconnecting circuit may be provided for each cell stack 20. That is, each of the disconnecting switch 141 and the protection element 142 may correspond to the cell stack 20 on a one-to-one basis.

Each of the disconnecting switches 141 may be on-off controllable in response to an external signal such as a relay or a MOSFET.

The smoothing unit 150 includes a plurality of capacitors 151. The number of capacitors 151 may be equal to the number of cell stacks 20. In this case, one capacitor 151 may be provided for each cell stack 20. That is, the caster 151 can correspond to the cell stack 20 on a one-to-one basis. Both ends of each capacitor 151 are connected in parallel to the respective cell stacks 20. 2, the first capacitor 151-1 is connected in parallel to the first cell stack 20-1 through two nodes N1 and N2, and the second capacitor 151-2 is connected in parallel to the first cell stack 20-1 through the two nodes N1 and N2. And the third capacitor 151-3 is connected in parallel to the third cell stack 20-3 via the nodes N3 and N4 in parallel with the second cell stack 20-2 through the nodes N2 and N3, Respectively. Each capacitor 151 suppresses a sudden voltage fluctuation between two nodes to which it is connected. Accordingly, each of the capacitors 151 prevents an instantaneous arc from occurring when the cell stack 20 connected in parallel with the cell stack 20 is electrically disconnected from the large current path.

Based on the first monitoring signal from the voltage measuring unit 110, the controller 170 determines whether there is an overcharge in the plurality of cell stacks 20-1 to 20-3. That is, the controller 170 determines whether or not each cell stack 20 is overcharged. The controller 170 can also calculate the number of overcharged cell stacks based on the first monitoring signal from the voltage measuring unit 110. [ To this end, the controller 170 compares the measured voltage from each cell stack 20 with a first reference voltage and / or a second reference voltage. At this time, the second reference voltage is higher than the first reference voltage. Preferably, the controller 170 may compare the voltage of each cell stack 20 with the first reference voltage and then compare it to the second reference voltage.

Each of the first reference voltage and the second reference voltage is utilized as a criterion for determining whether the cell stack 20 is overcharged. That is, the controller 170 determines that the cell stack 20 charged to a voltage equal to or higher than the first reference voltage is in the overcharge state. In addition, the controller 170 controls the bypass unit 120 such that only a part of the charge current is supplied to the cell stack 20 charged to a voltage equal to or higher than the first reference voltage and lower than the second reference voltage. Hereinafter, a state in which the voltage is equal to or higher than the first reference voltage and is lower than the second reference voltage is referred to as a 'first overcharge state'.

In addition, the controller 170 controls the bypass unit 120 and the disconnecting unit 140 such that the charge current is not supplied to the cell stack 20 charged to a voltage equal to or higher than the second reference voltage. In detail, the controller 170 controls the disconnecting unit 140 to electrically remove the charged cell stack 20 from the high current path to a voltage equal to or higher than the second reference voltage. The controller 170 then controls the bypass unit 120 so that the bypass path constituting the large current path is replaced by a bypass path in the battery pack 1 instead of each cell stack 20 electrically removed from the large current path . Hereinafter, a state in which the voltage is equal to or higher than the second reference voltage will be referred to as a " second overcharge state ".

On the other hand, the state of health (SOH) is gradually lowered as the battery cell 21 included in each cell stack 20 is repeatedly charged and discharged. That is, as each battery cell 21 is degenerated, the maximum value of the amount of charge storable in the cell stack 20 containing it decreases. Thus, in a general situation, if the same charge current is supplied to two or more cell stacks 20 that are fully charged, the cell stack 20 having the lowest SOH will quickly reach the overcharge state.

However, due to environmental factors such as temperature, a measurement error of the voltage measuring unit 110, or an operation error of the controller 170, the cell stack 20 having a relatively high SOH may be a cell stack having a relatively low SOH 20 may be temporarily determined to have reached the overcharge state. Therefore, it may not be desirable to electrically isolate the cell stack 20 determined to be in the overcharge state only once from the large current path. Obviously, in the long term, the lower the SOH of the cell stack 20, the higher the frequency of reaching the overcharged state.

In view of this point, the controller 170 can update the overcharge count of each cell stack 20 determined to be overcharged each time the cell stack 20 is determined to be overcharged. For example, when the voltage of the first cell stack 20-1 with the overcharge count k reaches the second reference voltage, the controller 170 changes the overcharge count of the first cell stack 20-1 from k to k + 1 < / RTI >

The controller 170 can also control the disconnecting unit 140 to electrically disconnect each cell stack 20 from the large current path when the number of overcharges reaches a predetermined threshold number of times. Here, the threshold number of times may be set in the controller 170 through a preliminary experiment. If the number of overcharges of any cell stack 20 is equal to or greater than the threshold number, it can be reliably relied upon that the SOH has dropped to such an extent that the cell stack 20 needs to be replaced.

On the other hand, while the charging power source is not connected to the battery pack 1, the controller 170 selectively controls each bypass circuit 130 based on the first monitoring signals S1-1 to S1-3, The voltage deviation between the plurality of cell stacks 20 can be mitigated. That is, the bypass unit 120 may perform a voltage balancing operation for the plurality of cell stacks 20.

FIG. 3 is a view showing an embodiment of the protective device shown in FIG. 2. FIG.

Referring to FIG. 3, each of the protection devices 142 may constitute a series circuit with one of the disconnecting switches 141 included in the disconnecting unit 140.

Each protective element 142 includes at least one fuse 143 and at least one heating resistor 144. For example, as shown in FIG. 3, each protection element 142 includes two fuses 143-1 and 143-2 connected in series to each other, and one end of the heating resistor 144 is connected to two fuses 143-1 and 143-2 -2) are connected in common. The other end of the fuse 143-1 is connected to an electrode (for example, an anode) of one of the cell stacks 20 and the other end of the fuse 143-2 is connected to one of the plurality of nodes N1 to N4 Can be connected.

Each fuse 143 included in the same protection element 142 is connected in series to each cell stack 20 between two nodes in which each cell stack 20 is connected in parallel to the bypass circuit 130. That is, between the two nodes N1 and N2 connected to the large current path of the first bypass circuit 130-1, the two fuses 143-1 and 143-2 of the first protection element 142-1 And is serially connected to the first cell stack 20-1. Two fuses 143-1 and 143-2 of the second protection element 142-2 are connected between the two nodes N2 and N3 connected to the large current path by the second bypass circuit 130-2 And is connected in series to the second cell stack 20-2. The two fuses 143-1 and 143-2 of the third protection element 142-3 are connected between the two nodes N3 and N4 connected to the large current path by the third bypass circuit 130-3 And is connected in series to the third cell stack 20-3.

Within each disconnect circuit, one end of at least one fuse 143 is connected to an electrode (e.g., an anode) of the cell stack 20.

In each disconnecting circuit, the heat generating resistor 144 has one end connected to at least one fuse 143 and the other end connected to the disconnecting switch 141. In each disconnecting circuit, the disconnecting switch 141 may be connected at one end to the other end of the heat generating resistor 144 and at the other end to ground or an electrode (e.g., a cathode) of the cell stack 20.

When at least one fuse 143 connected thereto is fused and the cell stack 20 connected to the fuse 143 in which either the positive terminal or the negative terminal is fused is blown Is electrically removed from the large current path.

2, when the first disconnecting switch 141-1 is controlled to be in the ON state, the charging current flows to the fuse 143-2 and the heating resistor 144 of the first protection element 142-1 . Of the two fuses 143-1 and 143-2 of the first protection device 142-1 by the heat generated when the charging current flows through the heating resistor 144 of the first protection element 142-1, (143-2) is fused. As a result, the first cell stack 20-1 and the node N1 are separated so that the first cell stack 20-1 is electrically completely disconnected from the portion between the two nodes N1 and N2 constituting the large current path do.

The controller 170 may control the off switch 141 corresponding to each cell stack 20-1 electrically disconnected from the large current path to an off state. For example, after the first cell stack 20-1 is electrically disconnected from the high current path as the first disconnecting switch 141-1 is controlled to be in the ON state, the controller 170 switches the first disconnecting switch 141-1 Can be returned to the off state.

Each of the protection elements 142 may further include a discharge induction resistor 145. The discharge induction resistor 145 is connected in parallel to the circuit in which the fuse 143-1 and the heating resistor 144 are connected in series. One end of the discharge induction resistor 145 is connected to the connection point between the fuse 143-1 and the cell stack 20 and the other end is connected to the connection point between the heating resistor 144 and the disconnecting switch 141 . Accordingly, regardless of the fuse of the fuse 143-1, the cell stack 20 can be connected to the disconnect switch 141 via the discharge induction resistor 145. [ The discharge path that can be provided to each cell stack 20 corresponds to a series connection circuit of the discharge induction resistor 145 and the disconnecting switch 141.

Preferably, the resistance value of the discharge induction resistor 145 is larger than the sum of the resistance value of the fuse 143-1 and the resistance value of the heating resistor 144. [ For example, the resistance value of the discharge induction resistor 145 is {(the resistance value of the fuse 143-1 + the resistance value of the heat generating resistor 144) x Q}. Where Q is a real number equal to or greater than 1, such as three.

Accordingly, when the fuse 143-2 of the two fuses 143-1 and 143-2 is fused first, the magnitude of the current flowing through the heat generating resistor 144 is larger than the magnitude of the current flowing through the discharge induction resistor 145 So that even the remaining fuse 143-1 is fused. When both the fuses 143-1 and 143-2 are fused, the resistance value of the discharge induction resistor 145 is considerably large, so that the magnitude of the current flowing through the discharge induction resistor 145 can be sufficiently suppressed.

Fig. 4 is a circuit diagram showing a circuit corresponding to the current limiting block B shown in Fig. 2. Fig.

Referring to FIG. 4, each current limiting block B shown in FIG. 2 is connected in series with the bypass switch 131 between two adjacent nodes on the large current path. Each bypass switch 131 may be on-off controlled in response to an external signal such as a relay or a MOSFET.

Each current limiting block B includes m current limiting circuits 132-1 to 132-m. Here, m is a natural number of 1 or more. Each current limit circuit 132 includes two or more resistors R connected in series or in series with each other. The number of resistors R included in each current limit circuit 132 may be equal to or different from each other.

When the resistance values of the current limit circuits 132 are the same, a charge current of the same magnitude flows in each current limit circuit. For example, when the charge current supplied to the current limit block B including 50 current limit circuits 132 is 200 A, a charge current of 4 A flows for each current limit circuit 132. If each current limit circuit 132 includes two resistors R connected in series and the resistance value of each resistor R is 0.1 ohm, each resistor R will consume 1.6W.

The controller 170 controls each bypass switch 131 to either ON or OFF based on the first monitoring signals S1-1 to S1-3 from the voltage measuring unit 110. [ A bypass path is provided to the cell stack 20 corresponding to the bypass circuit 130 including the bypass switch 131 that is controlled in the ON state.

Based on the first monitoring signals S1-1 to S1-3 from the voltage measuring unit 110 and the second monitoring signal S2 from the current measuring unit 160, The switch 131 may be controlled to be either in an on state or in an off state. For example, even if there is no cell stack determined to be overcharged in the battery pack 1, if the magnitude of the charge current notified by the second monitoring signal S2 corresponds to an overcurrent greater than a predetermined current level, 170 may control the bypass unit 120 to provide a bypass path to at least one cell stack 20.

FIGS. 5 and 6 are diagrams showing two implementations of the current limiting block shown in FIG.

First, FIG. 5 shows an embodiment in which a plurality of current limiting circuits included in the current limiting block B have the same resistance value with each other. For the sake of understanding, it is assumed that five current limit circuits 132-1 through 132-5, each consisting of a series connection of two resistors R having the same resistance value, are included in the current limit block B. The current limiting block B may further include a substrate 133 on which the five current limiting circuits 132-1 through 132-5 are mounted and a conductive pattern 134 formed on the substrate 133. [ The five current limiting circuits 132-1 through 132-5 are electrically connected in parallel to each other via the conductive pattern 134. [

At this time, the current limiting circuits 132-1 to 132-5 are spaced apart from each other by a predetermined distance along a predetermined direction. Namely, the second current limiting circuit 132-2 is separated from the first current limiting circuit 132-1 by W1, the third current limiting circuit 132-3 is separated from the second current limiting circuit 132-2, The fourth current limiting circuit 132-4 is spaced apart from the third current limiting circuit 132-3 by W3 and the fifth current limiting circuit 132-5 and the fourth current limiting circuit 132-5 are spaced apart from each other by W2, 132-4.

Even if a charging current of the same size flows in the current limiting circuits 132-1 to 132-5, the current limiting circuit (for example, 132-3) mounted in the central portion of the substrate 133 has another current limiting circuit -1, and 132-5 can be concentrated. If W1 = W2 = W3 = W3, a temperature imbalance may occur in which the temperature becomes higher toward the center of the substrate 133. [ To alleviate this problem, the distance between the two current limiting circuits 132-1 to 132-5 adjacent to each other toward the center of the substrate 133 can be increased. For example, W2, W3> W1, W4.

Thus, compared with the structure in which the distance between the two current limiting circuits adjacent to each other among the current limiting circuits 132-1 through 132-5 is equally mounted, the resistance R of the current limiting circuits 132-1 through 132-5 Can be smoothly discharged to the outside without concentrating on the central portion of the substrate 133. [

Next, Fig. 6 shows an embodiment in which a plurality of current limiting circuits included in the current limiting block B have different resistance values. For ease of understanding, three current limiting circuits 132-1 through 132-3 having different numbers of resistors R are shown as being included in the current limiting block B.

6, the first current limiting circuit 132-1 includes three resistors R, the second current limiting circuit 132-2 includes two resistors R, a third current limiting circuit 132 -3) includes one resistor (R). In this case, the resistance value of the first current limiting circuit 132-1 is three times that of the third current limiting circuit 132-3, and the resistance value of the second current limiting circuit 132-2 is the third current limiting circuit 132-3. (132-3).

Since the voltages applied to the three current limiting circuits 132-1 to 132-3 connected in parallel to each other are the same, the charging current flowing through the third current limiting circuit 132-3 having the smallest resistance value is the most The charging current flowing through the first current limiting circuit 132-1 having the largest and largest resistance value is the smallest.

The amount of heat generated by the first current limiting circuit 132-1 located closest to the cell stack 20 is the least and the amount of heat generated by the third current limiting circuit 132-3 located the farthest from the cell stack 20 Is the largest.

The three current limit circuits 132-1 through 132-3 may be different in distance from one cell stack 20 to which they are connected in parallel. Preferably, the current limiting circuit comprising a small number of resistors R is preferably located relatively far away from the cell stack 20.

For example, the first current limiting circuit 132-1 is mounted on the substrate 133 so as to be positioned closest to the cell stack 20, and the second current limiting circuit 132-2 is mounted on the first current limiting circuit 132- The third current limiting circuit 132-3 is further spaced from the cell stack 20 by W5 and the third current limiting circuit 132-3 is further spaced from the cell stack 20 by W6 than the second current limiting circuit 132-2. 133, it is possible to minimize the temperature rise of the overcharged cell stack 20, as compared with the opposite case.

7 to 9 are diagrams referred to in describing the operation of the circuit shown in Fig. For convenience of explanation, it is assumed that each protection element 142 is configured as shown in FIG.

First, FIG. 7 illustrates a case where all of the first to third cell stacks 20-1 to 20-3 are not overcharged. The controller 170 controls all the disconnecting switches 141-1 to 141-3 to the off state. Thus, the single cell stack 20 included in the battery pack 1 is also not electrically removed from the large current path. At the same time, the controller 170 controls all the bypass switches 131-1 to 131-3 to be in an off state. Thereby, there is not a single bypass path in the battery pack 1. As a result, a charge current I _C of the same size is supplied to all the cell stacks 20-1 to 20-3.

Next, FIG. 8 shows that the overcharge times of the first to third cell stacks 20-1 to 20-3 are all less than the threshold number, the first cell stack 20-1 is in the first overcharge state, And the third cell stacks 20-2 and 20-3 are not overcharged.

In this case, all of the first to third cell stacks 20-1 to 20-3 can be electrically isolated from the large current path, and only a part of the charge current I _{C can be} supplied to the first cell stack 20-1 It needs to be supplied.

To this end, the controller 170 controls all the disconnecting switches 141-1 to 141-3 to the OFF state similar to FIG. At the same time, the controller 170 controls the first bypass switch 131-1 to the ON state and controls the second and third bypass switches 131-2 and 131-3 to the OFF state. In this way, the contrast with FIG. 7, a portion the first bypass switch 131-1 for (I _{C_1)} constitutes a bypass path provided to the first cell stack (20-1) of the charging current (I _C) and a first flow through the current limiting block (B-1), the remainder of the charging current (I _C) (I _{C_2)} is supplied to the first cell stack 20-1. Here, the I _C = I + I _{C_1 C_ 2.}

As a result, the magnitude of the charging current supplied to the first cell stack 20-1 becomes smaller than the magnitude of the charging current supplied to the second and third cell stacks 20-2 and 20-3, The cell stack 20-1 is charged more slowly than the second and third cell stacks 20-2 and 20-3.

9, the first cell stack 20-1 and the second cell stack 20-2 of the first through third cell stacks 20-1 through 20-3 are in an overcharged state, The overcharge times of the first cell stack 20-1 reach the threshold number of times and the overcharge times of the remaining two cell stacks 20-2 and 20-3 reach the threshold number of times .

In this case, the first cell stack 20-1 in which the number of times of overcharge reaches the threshold number is electrically disconnected from the large current path, and only a part of the charge current I _C is supplied to the second cell stack 20-2 Needs to be.

To this end, the controller 170 controls the first disconnecting switch 141-1 to the ON state and the second and third disconnecting switches 141-2 and 141-3 to the OFF state. Thus, by the heat generation of the heat generating resistor 144 included in the first protection element 142-1 connected to the first short-circuiting switch 141-1, the two fuses included in the first protection element 142-1 At least the fuse 143-2 out of the first cell stacks 143-1 and 143-2 is fused so that the first cell stack 20-1 is electrically removed from the large current path.

At the same time, the controller 170 controls the first and second bypass switches 131-1 and 131-2 to be in the ON state and the third bypass switch 131-3 to the OFF state. Thus, a bypass path is provided to the first and second cell stacks 20-1 and 20-2. The bypass path provided to the first cell stack 20-1 constitutes a large current path instead of the first cell stack 20-1. That is, all of the charge current I _C flows through the bypass path provided to the first cell stack 20-1. Further, the bypass path provided to the second cell stack 20-2 constitutes a large current path together with the second cell stack 20-2. That is, over some (I _{C_3)} flows through the bypass path provided to the second cell stack 20-2, and the other (I _{C_4)} of the second cell stack 20-2 of the charging current (I _C) Flow. Here, the I _C = I + I _{C_3 C_ 4.}

The charging current I _C can not be supplied to the first cell stack 20-1 electrically isolated from the large current path and the charging current I _{C_4} supplied to the second cell stack 20-2 The size is smaller than the charge current I _C supplied to the third cell stack 20-3. As a result, charging of the first cell stack 20-1 is stopped, and the second cell stack 20-2 is charged more slowly than the third cell stack 20-3.

On the other hand, the disconnecting unit 140 can provide a discharge path to each cell stack 20 electrically disconnected from the large current path. For example, as shown in FIG. 9, a first cell stack (not shown) electrically isolated from a large current path through a discharge induction resistor 145 of the first protection device 142-1 and a first disconnecting switch 141-1 20-1 is connected to the other one of the positive terminal and the negative terminal. Therefore, after the fuse 143-2 of the first protection element 142-1 is fused, the discharge current I _D from the first cell stack 20-1 flows to the discharge induction resistor 145 . That is, as electric energy stored in the first cell stack 20-1 electrically disconnected from the large current path is consumed through the discharge induction resistor 145, the voltage of the first cell stack 20-1 Falls below the second reference voltage, and when a little more time passes, it falls below the first reference voltage and can escape from the overcharged state.

The bypass path and the discharge path provided to each cell stack 20 electrically isolated from the large current path are electrically independent from each other. That is, the discharging process of each cell stack (e.g., 20-1 of FIG. 9) electrically isolated from the large current path and the discharging process of each cell stack (for example, 20-2 and 20-3 of FIG. 9) Can be performed simultaneously.

2 and 7 to 9 show that the heat generating resistor 144, the discharge induction resistor 145, and the current limiting block B are all disposed on the same side with respect to each cell stack 20. However, This is merely an example. For example, any one of the heat generating resistor 144, the discharge induction resistor 145, and the current limiting block B is disposed on the opposite side to the rest of the cell stack 20, so that the heat generating resistor 144, The resistance of the resistor 145 and the current limiting block B may not be concentrated on only a portion of each cell stack 20.

10 is a flowchart showing an overcharge prevention method according to another embodiment of the present invention. The overcharge prevention method according to the flowchart of Fig. 10 is executed to protect a plurality of cell stacks connected in series with each other from the overcharge state individually as shown in Fig.

Referring to Fig. 10, in step S101, the controller 170 receives a first monitoring signal indicating the voltage of each cell stack 20. The first monitoring signal received by the controller 170 is output from the voltage measuring unit 110.

In step S102, the controller 170 determines, based on the first monitoring signal, whether or not there is an overcharged cell stack in the battery pack 1. If the result of step S102 is YES, step S103 is performed. On the other hand, if the result of step S102 is "NO ", the process may return to step S101 or the method may be terminated.

In step S103, the controller 170 updates the overcharge count of each cell stack determined to be overcharged.

In step S104, the controller 170 determines whether there is a cell stack in which the number of times of overcharge reaches the threshold number of times. If the result of step S104 is YES, step S105 is performed. On the other hand, if the result of step S104 is "NO ", the process proceeds to step S106.

In step S105, the controller 170 turns on the disconnecting switch 141 corresponding to each cell stack 20 in which the number of times of overcharge reaches the threshold number of times. That is, the disconnecting switch 141 connected to the heating resistor 144 of the protection element 142 connected to each cell stack 20 in which the number of times of overcharge reaches the threshold number of times is controlled to be in the ON state. At this time, the controller 170 can control the disconnecting switch 141 corresponding to the remaining cell stack 20 in which the number of times of overcharge has not reached the threshold number to be in the off state. Thus, only the cell stack 20 in which the number of times of overcharging reaches the threshold number is electrically disconnected from the large current path.

For example, when the number of times of overcharge of the first cell stack 20-1 reaches the threshold number of times, the controller 170 controls only the first disconnecting switch 141-1 to be on-state as shown in Fig. 9, And the third-stage switches 141-2 and 141-3 can be controlled to be in an OFF state. The fuse 143 of the first protection element 142-1 is fused so that the first cell stack 20-1 is turned on by the two nodes of the large current path, (N1, N2).

In step S106, the controller 170 controls the bypass switch 131 of the bypass circuit 130 corresponding to each overcharged cell stack 20 to the ON state. At this time, the controller 170 can control the bypass switch 131 of the bypass circuit 130 corresponding to the remaining cell stack 20 that is not overcharged to be in the OFF state. Thus, the bypass path is provided only to the overcharged cell stack 20.

For example, when the first and second cell stacks 20-1 and 20-2 are in an overcharged state as shown in FIG. 9, the controller 170 is connected to the first and second cell stacks 20-1 and 20-2 The third bypass switch 131-3 corresponding to the third cell stack 20-3 is controlled to be in the off state, Can be controlled.

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.

1: Battery pack
10: Battery module
20: cell stack
21: Battery cell
100: overcharge prevention device
110: voltage measuring unit
111: Voltage sensor
120: Bypass section
130: bypass circuit
131: Bypass switch
140:
141: disconnect switch
142: Protection element
150: Smooth part
151: Capacitor
160: Current measuring unit
170: Controller

Claims (12)

An apparatus for preventing overcharging of a plurality of cell stacks connected in series in a large current path,
A voltage measuring unit measuring a voltage of each cell stack and generating a first monitoring signal indicating a measured voltage;
A bypass unit having a plurality of bypass circuits configured to selectively provide a bypass path to each cell stack;
And a controller communicably connected to the voltage measuring unit and the bypass unit,
Wherein each bypass circuit includes:
Bypass switch; And
And a plurality of current limiting circuits connected in parallel to each cell stack through the bypass switch,
The controller comprising:
And controls each of the bypass switches based on a first monitoring signal from the voltage measuring unit.
The method according to claim 1,
Each of the current limiting circuits includes:
And at least two resistors connected in series or in series with each other.
The method according to claim 1,
Wherein one of said plurality of current limit circuits is spaced a predetermined distance from the rest.
The method according to claim 1,
The voltage measuring unit includes:
A plurality of voltage sensors connected in parallel to each of the cell stacks;
And an overcharge prevention device.
The method according to claim 1,
A disconnecting unit electrically disconnectable from each of the cell stacks;
Further comprising an overcharge prevention device.
6. The method of claim 5,
The disconnecting unit
A fuse that is connected in series to each cell stack between two cell stacks and two nodes in which the plurality of current limiting circuits are connected in parallel; And a plurality of protection elements each having an end connected to the fuse; And
A plurality of disconnecting switches each having one end connected to the other end of each of the heat generating resistors and the other end connected to an electrode of each cell stack;
And an overcharge prevention device.
6. The method of claim 5,
The controller comprising:
And determines whether or not each cell stack is overcharged based on the first monitoring signal.
The method according to claim 6,
The controller comprising:
And controls the disconnecting unit to electrically disconnect each cell stack determined to be overcharged from the large current path.
The method according to claim 6,
And updates the overcharge count of each cell stack each time the cell stack is determined to be overcharged.
10. The method of claim 9,
The controller comprising:
And turns on each of the disconnecting switches connected in series to each cell stack in which the number of times of overcharge reaches a predetermined threshold number of times.
The method according to claim 1,
A plurality of capacitors connected in parallel to the respective bypass circuits, respectively;
Further comprising an overcharge prevention device.
An overcharge protection device according to any one of claims 1 to 11; And
A plurality of cell stacks connected in series in a large current path,
Wherein the overcharge protection device performs an overcharge protection operation for each of the cell stacks.

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