KR101093826B1 - Protect circuit of secondary battery - Google Patents

Abstract

The present invention relates to a protection circuit of a battery pack, and a technical problem to be solved is to provide a protection circuit that can accommodate the current capacity of a high capacity battery pack.

To this end, the gist of the solution according to the present invention connects a fuse to a large current path between a battery cell and an external terminal, and the fuse is provided with a self control protector by winding a hot wire. Then, the current flows through the hot wire during overcharge or overdischarge, thereby forcibly melting the fuse at a high temperature, thereby preventing overcharge or overdischarge of the battery cell.

Such an important use of the present invention can be used for the protection circuit of a battery cell of high capacity in which a plurality of cells are connected in parallel.

Self controll protector (SCP), fuses, hot wires, battery cells, sensor resistors

Description

Protect circuit of secondary battery

1 is a block diagram illustrating a protection circuit configuration of a conventional battery pack.

FIG. 2A is a circuit diagram illustrating a protection circuit configuration of a battery pack according to the present invention, and FIG. 2B is an explanatory view illustrating fuses and heating wires, which are main components of a self control protector, in the protection circuit of a battery pack according to the present invention.

3 is a circuit diagram illustrating a state in which the self control protector is operated by overcharging during charging in the protection circuit of the battery pack according to the present invention.

4 is a circuit diagram illustrating a state in which the self control protector operates by over discharge during discharge in the protection circuit of the battery pack according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100; Protective circuit of a battery pack according to the present invention

110; Battery cell 120; External terminals

130; Sensor resistance 140; Control

150; Switch element 160; Self control protectors

161,165; Fuse 162; thermic rays

163; Bypass line 164; Node

166,167; diode

The present invention relates to a protection circuit of a battery pack, and more particularly, to a secondary protection circuit of a battery pack capable of secondarily protecting the battery pack in the event of a failure of the primary protection circuit or the charge / discharge control FET device. .

In general, the battery pack is provided with a primary protection circuit and a secondary protection circuit together with a charge / discharge circuit to safely protect the battery cell from overcharging, overdischarging, or an external short. The primary protection circuit normally opens a large current path temporarily during overcharge or overdischarge. In other words, when the battery is in a normal charging or discharging state, the large current path is connected again to allow the battery cells to be charged or discharged. However, the secondary protection circuit completely opens the large current path so that it cannot be used again when the primary protection circuit does not operate normally or the charge / discharge control FET device connected to the large current path fails. That is, even in a normal charging or discharging state, the large current path is still open, and eventually, the entire circuit needs to be replaced with a new part or a specific part.

1, a protection circuit 100 '(i.e., a secondary protection circuit) of such a conventional battery pack is shown as a block diagram.

As shown, the protection circuit 100 ′ of the conventional battery pack is connected to the battery cell 110 ′ capable of charging and discharging, and connected to the battery cell 110 ′ in parallel to be charged by an external charger (not shown). A sensor resistor 130 'installed between the external terminal 120' and enabling the discharge to the external set and between the external terminal 120 'and the battery cell 110' to detect overcharge and overdischarge. And a controller 140 'that outputs a predetermined signal when it is determined to be overcharged or overdischarged by the sensor resistor 130', and a switch element 150 that is turned on or off by an output signal of the controller 140 '. '), Which is connected in series between the external terminal 120' and the battery cell 110 ', and is melted by an ON signal of the switch element 150', thereby safely protecting the battery cell 110 '. A fuse 160 '.

As described above, when the value detected by the sensor resistor 130 'is determined to be overcharged or overdischarged, the control unit 140' may control the switch circuit 150 'of the conventional battery pack. Outputs a predetermined signal. Then, by operating the fuse 160 'installed in the high current path while the switch element 150' is turned on, the battery cell 110 'is protected from overcharge or overdischarge.

However, the protection circuit 100 ′ of such a conventional battery pack has recently increased in capacity due to the high capacity of the battery cell 110 ′, but there is a problem in that it cannot accommodate the increased current capacity. For example, since the conventional fuse 160 'is designed to withstand a current of approximately 12A, when the supply current exceeds this value due to an increase in the capacity of the battery cell 110', the fuse 160 ' There is a problem of not working properly, rugged or broken. That is, the recent battery cell 110 'flows a current of 12A or more as described above. In this case, although the fuse 160' is in a normal charging / discharging condition, the battery cell 110 'is not melted or damaged to perform a normal function. have.

In addition, the above-described fuse 160 'is already known to have a patent from a Japanese company, and it is difficult for a domestic company to produce and sell a protection circuit by using the same. In particular, the fuse 160' is exported to Japan, the United States, and Europe. Is expected to be a major obstacle.

The present invention is to overcome the above-mentioned conventional problems, an object of the present invention to provide a protection circuit of a battery pack that can safely protect a large capacity battery cell during overcharge or over discharge.

In order to achieve the above object, a protection circuit of a battery pack according to the present invention includes a battery cell in which at least one cell capable of charging and discharging is connected in series and connected to the battery cell in parallel to be charged by an external charger or to an external set. An external terminal for discharging, at least one sensor resistor connected to a large current path between the external terminal and the battery cell to detect an overcharge and overdischarge state, and determined as an overcharge or overdischarge state by the sensor resistance A fuse is connected in series with a control unit for outputting a predetermined signal, a switch element turned on and off by the output signal of the control unit, and a large current path between the external terminal and the battery cell, and the fuse is wound with a hot wire. The heating wire is connected to the switch element, and by the operation of the switch element As the group fuse the carpet comprises a self control protector to block the overcharge or over-discharge of the battery cell.

The fuse of the self control protector may be fused at a temperature of 110 ~ 130 ℃.

The heating wire of the self control protector may be an operating temperature of 120 ~ 140 ℃.

The switch element may be an n-channel field effect transistor.

The switch element may be a p-channel field effect transistor.

One end of the heating wire may be connected to the source of the field effect transistor, and the other end thereof may be grounded.

A bypass line may be further connected in parallel to both ends of the fuse, and a drain of the field effect transistor may be connected to the bypass line through a node.

Between the node of the bypass line and the external terminal, a diode that is forward in the direction of the battery cell from the external terminal can be further connected so that the charging current is supplied to the hot wire when the switch element is turned on during overcharging.

Between the node of the bypass line and the battery cell, a diode forward in the direction of the external terminal in the battery cell can be further connected so that the discharge current is supplied to the hot wire when the switch element is turned on during overdischarge.

A fuse that is melted when a current of a predetermined value or more flows between the node and the drain of the field effect transistor may be further connected.

As described above, in the protection circuit of the battery pack according to the present invention, a self-control protector made of a hot wire and a fuse is connected to a large current path, thereby sufficiently accommodating a large capacity battery cell. That is, the fuse used in the self-control protector can be easily designed with a capacity that can accommodate a large battery cell, and the heat or temperature supplied to the carpet can be easily implemented by adjusting the number of turns of the heating wire. Because there is.

In addition, the protection circuit of the battery pack according to the present invention as described above can be designed to avoid the components already possessed as a source patent in a foreign company can be manufactured and sold in the domestic, and also the battery pack to which the present invention is applied to foreign countries If they are exported, foreign patents can be sufficiently avoided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

Referring to FIG. 2A, a protection circuit of a battery pack according to the present invention is shown, and referring to FIG. 2B, a fuse and a heating wire, which are main components of a self control protector, are shown in the protection circuit of a battery pack according to the present invention. have.

As shown, the protection circuit 100 of the battery pack according to the present invention includes a battery cell 110, an external terminal 120 connected in parallel to the battery cell 110, and a sensor resistor 130 connected on a large current path. ), A control unit 140 for receiving a predetermined signal from the sensor resistor 130 to perform a predetermined control, a switch element 150 operated by the control unit 140, the switch element 150 and a large current It is installed between the path includes a self-control protector 160 to block the large current path during overcharge or over discharge.                     

The battery cell 110 is a secondary battery that can be charged and discharged, which is charged to a predetermined voltage and current by an external charger, or discharges to an external set at a predetermined voltage and current. In addition, the battery cell 110 may be a high capacity battery cell 110 in which at least one cell is connected in series. For example, such a battery cell 110 may be 4S1P (4 serial 1 parallel) in which 4 cells are connected in series and in parallel.

The external terminal 120 includes two + poles P + and-poles P−, which are connected to the battery cell 110 in parallel. In addition, the external terminal 120 is directly connected to an external charger or an external set. Therefore, when the external terminal 120 is connected to the charger, the battery cell 110 is charged, and when the external terminal 120 is connected to the external set, the battery cell 110 is discharged.

The sensor resistor 130 is connected between the external terminal 120 and the battery cell 110. That is, they are connected on a large current path. Therefore, since the resistance value of the sensor resistor 130 is known in advance, when the voltage applied to the sensor resistor 130 is detected, not only the charge / discharge voltage of the battery cell 110 but also the charge / discharge current are indirectly detected. You can do it. That is, the sensor resistor 130 may detect an overcharge voltage, an overdischarge voltage, an overcharge current, an overdischarge current, and the like of the battery cell 110. Of course, the detected value is transmitted to the controller 140. In addition, although the sensor resistor 130 is shown as one in the drawing, as described above, when the battery cell 110 is composed of a plurality of cells connected in series and in parallel, the charge / discharge voltage and current may be detected for each cell. The sensor resistor 130 may be connected so that.                     

When the controller 140 receives the overcharge and overdischarge signals from the sensor resistor 130, the controller 140 inverts and outputs a predetermined signal to the switch element 150. That is, if the low state is applied to the switch, the state is inverted to the high state and if the high state is applied, the state is inverted to the low state. Although not shown in more detail, the control unit 140 may include a comparison circuit and a logic circuit connected to the sensor resistor 130. Of course, a reference voltage is applied to the comparison circuit. Thus, for example, when the voltage sensed from the sensor resistor 130 becomes higher than the reference voltage, the comparison circuit outputs a predetermined signal, which is sent to the switch element 150 by the logic circuit. Is output.

The switch element 150 is an element turned on or off by an output signal of the controller 140. For example, the switch element 150 may be an n-channel field effect transistor that is turned on when a high signal is input to a gate. In addition, the switch element 150 may be a p-channel field effect transistor that is turned on when a low signal is input to a gate.

The self control protector 160 includes a fuse 161 connected to a large current path between the external terminal 120 and the battery cell 110, and a heating wire 162 wound around the fuse 161 a plurality of times. That is, as shown in FIG. 2B, the self-control protector 160 is provided with a fuse 161 that is fused at a predetermined temperature inside the insulator 162a (for example, a cylindrical glass). The heating wire 162 may be wound around the outside.

Here, the fuse 161 is preferably used to be melted at a temperature of approximately 110 ~ 130 ℃. If the melting temperature of the fuse 161 is about 110 ° C. or less, the fuse 161 may be melted during the aging process of the battery pack manufacturing process. In addition, when the melting temperature of the fuse 161 is 130 ° C. or higher, there is a risk that the battery pack is swelled and explodes before the fuse 161 is melted.

In addition, the heating wire 162 wound a plurality of times in the fuse 161 is preferably used that the operating temperature is approximately 120 ~ 140 ℃. If the operating temperature is 120 ° C. or less, the fuse 161 may not be fused. In addition, when the operating temperature is 140 ° C. or higher, other components may be affected and the protection circuit may malfunction. Of course, the operating temperature of the heating wire 162 is possible, by adjusting the number of turns of the heating wire 162.

One end of the heating wire 162 may be connected to the switch element 150, that is, the source of the field effect transistor, and the other end may be grounded. Therefore, when the switch element 150 is turned on, current is supplied to the heating wire 162 through the drain and the source.

Meanwhile, a bypass line 163 is further connected in parallel to both ends of the fuse 161, that is, the large current path. Further, the drain line of the switch element 150, that is, the field effect transistor, is connected to the bypass line 163 through the node 164. Of course, another fuse 165 that is fused when a predetermined amount or more of current flows between the switch element 150 and the node 164 may be connected. The fuse 165 may have a capacity of about 0.5 to 2 A, so that too much current does not flow in the heating wire 162.

In addition, a diode 166 forward in the direction of the battery cell 110 from the external terminal 120 is further connected to the bypass line 163 between the node 164 and the external terminal 120. The diode 166 is supplied to the heating wire 162 through the diode 166, the node 164, the fuse 165, and the switch element 150 when the switch element 150 operates when overcharged. Be sure to

In addition, another diode 167 forward in the direction of the external terminal 120 from the battery cell 110 is further connected to the bypass line 163 between the node 164 and the battery cell 110. The diode 167 is supplied to the heating wire 162 through the diode 167, the node 164, the fuse 165 and the switch element 150 when the switch element 150 is operated during over discharge. Be sure to

In the present invention having such a configuration, the switch element 150 operates during overcharging or overdischarging, and a part of the charging current or the discharging current is supplied to the heating wire 162 of the self control protector 160, and thus the fuse 161. ) Is forcibly fused, thereby preventing overcharging or overdischarging the battery cell 110.

Referring to FIG. 3, a state in which the self control protector operates by overcharging during charging in the protection circuit of the battery pack according to the present invention is illustrated.

As shown, first, the external charger 200 is connected to the external terminal 120. That is, the + pole of the external charger 200 is connected to the + pole P + of the external terminal 120, and the-pole of the external charger 200 is connected to the-pole P-of the external terminal 120. The battery cell 110 is charged.

When the battery cell 110 is in an overcharged state during the charging, the controller 140 detects this through the sensor resistor 130.

Then, the control unit 140 outputs a high or low signal to the switch element 150, so that the switch element 150 is turned on.

Here, before the switch element 150 is turned on, the charging current I1 is controlled by the positive electrode P + of the external terminal 120 and the fuse 161 of the self control protector 160. It is in the state of flowing to the pole B +.

However, when the switch element 150 is turned on as described above, some of the charging currents I2 flow through the bypass line 163. That is, the bypass current I2 is supplied to the heating wire 162 through the diode 166, the fuse 165, the drain and the source of the switch element 150. Therefore, the heating wire 162 generates heat to a predetermined temperature, thereby fusion of the fuse 161 therein, thereby preventing overcharging of the battery cell 110.

Referring to FIG. 4, a state in which the self control protector is operated by over discharge during discharging in the protection circuit of the battery pack according to the present invention is illustrated.

As shown in the drawing, an external set 300 is connected to an external terminal 120. That is, the + pole of the external set 300 is connected to the + pole P + of the external terminal 120, and the-pole of the external set 300 is connected to the-pole P-of the external terminal 120. , The battery cell 110 is discharged.                     

If the battery cell 110 is in an over-discharge state during the discharge, the controller 140 detects this through the sensor resistor 130.

Then, the control unit 140 outputs a high or low signal to the switch element 150, so that the switch element 150 is turned on.

Here, before the switch element 150 is turned on, the discharge current I1 is discharged from the external terminal 120 through the positive electrode B + of the battery cell 110 and the fuse 161 of the self control protector 160. It is a state flowing to the pole (P +).

However, when the switch element 150 is turned on as described above, some of the discharge currents I2 flow through the bypass line 163. That is, the bypass current I2 is supplied to the heating wire 162 through the diode 167, the fuse 165, the drain and the source of the switch element 150. Accordingly, the heating wire 162 generates heat to a predetermined temperature, thereby fusing the fuse 161 therein to prevent over discharge of the battery cell 110.

As described above, the protection circuit of the battery pack according to the present invention is connected to a self-control protector made of a hot wire and a fuse in a large current path, thereby having an effect of sufficiently accommodating a large capacity battery cell. That is, the fuse used in the self-control protector can be easily designed with a capacity that can accommodate a large capacity battery cell, and the heat or temperature supplied for fusion can be easily implemented by adjusting the number of turns of the heating wire. have.

In addition, the protection circuit of the battery pack according to the present invention as described above can be designed to avoid the components already possessed as a source patent in a foreign company can be manufactured and sold in Korea, and also the battery to which the present invention is applied to foreign countries Exporting packs can effectively avoid foreign patents.

What has been described above is only one embodiment for implementing the protection circuit of the battery pack according to the present invention, the present invention is not limited to the above embodiment, as claimed in the following claims of the present invention Without departing from the gist of the present invention, one of ordinary skill in the art will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (10)

A battery cell in which at least one cell capable of charging and discharging is connected in series; An external terminal connected in parallel to the battery cells to allow charging by an external charger or discharging to an external set; At least one sensor resistor connected to the high current path between the external terminal and the battery cell to sense an overcharge and an overdischarge state; A controller for outputting a predetermined signal when it is determined that the sensor is in an overcharged or overdischarged state; A switch element turned on and off by an output signal of the controller; And, A fuse is connected in series to a large current path between the external terminal and the battery cell, and the fuse is wound with a hot wire, and the hot wire is connected to the switch element, whereby the fuse is melted by the operation of the switch element. Including self-control protector which blocks overcharge and overdischarge of battery cell, The switch element is a field effect transistor, A bypass line is further connected in parallel to both ends of the fuse, and a drain of the field effect transistor is connected to the bypass line through a node. The protection circuit of claim 1, wherein the fuse of the self control protector is melted at a temperature of 110 ° C. to 130 ° C. 3. The protection circuit of a battery pack according to claim 1, wherein the heating wire of the self control protector has an operating temperature of 120 to 140 ° C. The protection circuit of claim 1, wherein the field effect transistor is an n-channel type. The protection circuit of claim 1, wherein the field effect transistor is a p-channel type. The protection circuit of claim 1, wherein one end of the heating wire is connected to a source of the field effect transistor and the other end is grounded. delete According to claim 1, Between the node of the bypass line and the external terminal, the diode further forward in the direction of the battery cell from the external terminal so that the charging current can be supplied to the hot wire when the switch element is turned on during overcharging. A protective circuit of a battery pack, characterized in that. The method of claim 1, wherein the diode of the forward line in the direction of the external terminal in the battery cell is further connected between the node of the bypass line and the battery cell so that the discharge current is supplied to the hot wire when the switch element is turned on during over discharge. A protective circuit of a battery pack, characterized in that. The protection circuit of claim 1, wherein a fuse melted when a current of a predetermined value or more flows between the node and the drain of the field effect transistor.

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