KR20060059679A - Battery pack - Google Patents

Abstract

The present invention relates to a battery pack, and the technical problem to be solved is to provide a battery pack that can further improve safety and reliability by preventing artificial overvoltage, reverse voltage, short, abnormal discharge, etc. of the pack power supply stage.

To this end, the gist of the solution method according to the present invention includes a bare cell connected in parallel to the pack power supply terminal, a protection circuit unit connected in parallel to the bare cell to sense charge / discharge voltage and current, and control processing the same according to a predetermined order; A charger or external device connected in series between the power supply terminal and the bare cell and simultaneously connected to the pack power supply terminal and the bare cell in series with a charge / discharge switch for controlling charging and discharging of the bare cell under the control of the protection circuit. A battery pack is disclosed that includes a control switch that is only on when connected to a set.

Battery Pack, Overcharge, Over Discharge, Switch, Field Effect Transistor

Description

Battery Pack {Battery pack}

1 is a circuit diagram illustrating a conventional battery pack.

2 is a circuit diagram illustrating a control state during overcharging of a conventional battery pack.

3 is a circuit diagram illustrating a control state during overdischarge of a conventional battery pack.

4 is a circuit diagram illustrating a battery pack according to the present invention.

5 is a simplified circuit diagram showing an operating state (off state) of a battery pack according to the present invention.

6 is a simplified circuit diagram showing an operating state (on state) of a battery pack according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100; Battery pack according to the present invention

110; Bare cell 120; Protective circuit part

130; Charge / discharge switch 131; Charge switch

132; Discharge switch 140; Control switch

141; First switch 142; Second switch

B +, B-; Bare cell anode cell power supply and cathode cell power supply

P +, P-; Positive pack power terminal, negative pack power terminal of battery pack

PT; Protection

R1, R2, R3, R4; resistance

C1, C2, C3, C4, C5, C6; Capacitor

The present invention relates to a battery pack, and more particularly, to a battery pack that can further improve safety and reliability by preventing artificial overvoltage, reverse voltage, short, abnormal discharge, and the like of the pack power supply stage.

In general, a battery pack is composed of a bare cell which performs only a pure charge / discharge operation, and a protection circuit that controls the charge / discharge state of the bare cell. In recent years, bare cells (for example, lithium ion batteries) have advantages of high energy density, but since they are dangerous, the function of a protection circuit for protecting consumers from overcharge or overdischarge becomes more important.

The configuration and operation of the battery pack having such a protection circuit will be described with reference to FIG. 1 as follows.

As shown, a conventional battery pack 10 'is connected to a pack cell terminal P +' and P- 'in parallel with a bare cell 11', and is connected in parallel with the bare cell 11 'and overcharged. And a protection circuit unit 12 'that detects overdischarge and the like and performs a control process in a predetermined order, and is connected in series between one side of the bare cell 11' and one side of the pack power supply terminal P- '. The charging / discharging switch 13 'is controlled by the protection circuit section 12'.

Here, the pack power terminal (P + ', P-') is connected to a charger or / and an external set.

In addition, the charge / discharge switch 13 'controls charge and the field effect transistor 13a' for charge control with the parasitic diode D1 ', and the field effect transistor for discharge control with the discharge and parasitic diode D2'. 13b ', each gate is connected to the protection circuit portion 12'.

In the drawings, reference numerals R1 and R2 denote antistatic resistors, and C1, C2 and C3 denote power supply fluctuation preventing capacitors.

In the conventional battery pack having such a configuration, when overcharging is performed on the bare cell through the pack power supply terminal, as shown in FIG. 2, the protection circuit unit turns off the charging switch to stop the overcharge state. In addition, when the over-discharge of the bare cell is made through the pack power supply terminal, as shown in FIG. 3, the protection circuit unit turns off the discharge switch to stop the over-discharge state.

However, such a conventional battery pack effectively prevents overcharging or overdischarging to some extent while being connected to a designated charger or an external set, but is connected to a charger, an external set that is not specified, or artificially overcharged or overcharged. There is a problem that it becomes considerably dangerous when electric charge, reverse charge, pack power supply short circuit, abnormal discharge, and the like are performed. For example, when a customer artificially overcharges, reverses, or shorts through a pack power supply, the protection circuit does not detect this quickly and overloads the charge / discharge switch. The circuit unit and the charge / discharge switch may be damaged. Of course, such damage may occur in the circuit board itself on which the protection circuit unit and the charge / discharge switch are mounted.

Such damage to the protection circuit unit, the charge / discharge switch, and the circuit board causes the battery pack to be exposed to overcharging or overdischarging. As a result, the battery pack is degraded, and various dangerous situations such as leakage, heat generation, smoke, fire, and rupture are caused. Will result.

The present invention is to overcome the above-mentioned conventional problems, an object of the present invention is to prevent the artificial overvoltage, reverse voltage, short, abnormal discharge, etc. of the pack power supply terminal, to further improve the safety and reliability of the battery pack To provide.

In order to achieve the above object, a battery pack according to the present invention includes a bare cell connected in parallel to a pack power supply terminal and a parallel connection to the bare cell to sense charge / discharge voltage and current, and to control and process the same in a predetermined order A charge / discharge switch connected in series between the circuit unit, the pack power supply terminal and the bare cell, and at the same time connected in series between the pack power supply terminal and the bare cell, controlling charge / discharge of the bare cell under control of the protection circuit unit, It includes a control switch that is on only when the pack power stage is connected to a designated charger or external set.

Here, the bare cell includes a positive cell power supply terminal and a negative cell power supply terminal, the pack power supply terminal is composed of a positive electrode pack power supply terminal and a negative electrode pack power supply terminal, the charge and discharge switch between the negative cell power supply terminal and the negative electrode pack power supply terminal. The control switch may be connected between the positive cell power supply terminal and the negative electrode pack power supply terminal.

The control switch may include at least one field effect transistor having a source and a drain connected in series to a cathode cell power supply terminal and a cathode pack power supply terminal of the bare cell, and a control capacitor connected between the gate and the cathode pack power supply terminal of the field effect transistor. And a protection stage connected between the gate and the control capacitor and connected to the negative pack power supply terminal when the battery pack is coupled to a designated charger or an external set.

In addition, the field effect transistor is turned off when the protection stage is open, the gate is held in a high state by the voltage charged in the control capacitor, the control when the protection stage is connected to the negative pack power supply terminal The capacitor may be discharged and the gate may be turned on to be in an on state.

As described above, in the present invention, the control switch is turned on only when the battery pack is connected to a predetermined charger or an external set, thereby enabling a state of charge and discharge.

Therefore, the battery pack is connected to an unspecified charger or an external set, or charging / discharging is essentially blocked at the time of artificial overcharge, reverse charge, and short, thereby increasing safety and reliability.

Of course, when the battery pack is connected to a designated charger or an external set, the present invention enables normal charge / discharge operation, and thus the protection circuit unit and the charge / discharge switch control the charge / discharge state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that those skilled in the art may easily implement the present invention.

4 is a circuit diagram illustrating a battery pack 100 according to the present invention.

As shown, the battery pack 100 according to the present invention includes a bare cell 110, a protection circuit unit 120, a charge / discharge switch 130, and a control switch 140.

First, the bare cell 110 is a conventional secondary battery capable of charging and discharging. For example, although a normal lithium ion battery, a lithium polymer battery, or the equivalent is possible, it does not limit the kind here. In addition, although the bare cell 110 is shown as one in the figure, the number of the bare cells 110 is also possible, and the number of the bare cells 110 is not limited in the present invention.

In addition, the bare cell 110 is connected in parallel with the pack power supply terminals (P +, P-). That is, the positive cell power terminal B + of the bare cell 110 is connected to the positive pack power terminal P + of the pack power terminal, and the negative cell power terminal B- of the bare cell 110 is connected to the pack power terminal. It is connected to the negative pack power supply terminal (P-).

The protection circuit unit 120 is connected to the bare cell 110 in parallel. Accordingly, the protection circuit unit 120 may sense the charge voltage and the discharge voltage of the bare cell 110, and perform a control process in a predetermined order according to the sensed charge / discharge voltage. The protection circuit unit 120 may be formed of a general integrated circuit or an equivalent circuit thereof, but is not limited thereto.

Subsequently, the charge / discharge switch 130 is connected in series between the bare cell 110 and the pack power supply terminals P + and P−. That is, the charge / discharge switch 130 is connected between the negative cell power terminal B- of the bare cell 110 and the negative electrode pack power terminal P- of the pack power terminal. In addition, the charge and discharge switch 130 may be composed of a charge switch 131 for controlling the state of charge and a discharge switch 132 for controlling the discharge state. Further, the charge switch 131 may be an n-channel field effect transistor having a parasitic diode D1, and the discharge switch 132 may be an n-channel field effect transistor having a parasitic diode D2. Of course, the gates of the respective field effect transistors are connected to the CO terminal and the DO terminal of the protection circuit unit 120, respectively, so that the field effect transistors are turned on by the high or low signal output from the protection circuit unit 120. The off state is controlled. In addition, capacitors C1 for preventing power fluctuations and protecting devices from static electricity and the like are connected to both ends of the charge / discharge switch 130 in parallel.

Meanwhile, one end of the charge / discharge switch 130 is connected to the VM terminal of the protection circuit unit 120 via the charge / discharge current sensing resistor R1. Therefore, the protection circuit unit 120 can calculate the charge / discharge current by sensing the voltage applied between the VSS terminal and the VM terminal. That is, since the resistance value of the charge / discharge current sensing resistor R1 is a known value, the current is calculated by sensing the voltage applied to the resistor R1. In addition, the bare cell 110 is connected to the antistatic resistor (R2) and the power supply variation preventing capacitor (C2) in parallel, and the protection circuit unit (2) between the antistatic resistor (R2) and the power supply variation preventing capacitor (C2). The VDD terminal of 120 is connected. Therefore, the protection circuit unit 120 can detect the charge / discharge voltage of the bare cell 110 using the VDD terminal and the VSS terminal.

Of course, the protection circuit unit 120 has a built-in comparator to perform a predetermined control process by comparing the charge-discharge voltage obtained from the VDD terminal and the VSS terminal and the charge-discharge current obtained from the VSS terminal and the VM terminal with a reference value.

The control switch 140 is connected in series between the bare cell 110 and the pack power supply terminals (P +, P-). That is, the control switch 140 is connected in series between the anode cell power supply terminal B + of the bare cell 110 and the anode pack power supply terminal P + of the pack power supply terminal. In addition, the control switch 140 may be connected to the first control switch 141 and the second control switch 142 in series. In other words, the control switch 140 may be at least one field effect transistor connected in series. In the drawing, two p-channel field effect transistors are connected in series. In the field effect transistor, a gate is connected between the charge / discharge switch 130 and the negative electrode pack power supply terminal P− via the antistatic resistor R3 and the control capacitor C3.

Here, the control switch 140 has a capacitor (C4) is connected in parallel at both ends in order to prevent power fluctuations and static electricity, and also between the resistor (R3) and the capacitor (C3) and between the positive electrode pack power supply terminal (P +) In addition, the capacitor (C5) is connected to prevent power fluctuations and static electricity. Furthermore, a resistor R4 and a capacitor C6 are connected between the two field effect transistors and the common gate to prevent power fluctuations and static electricity.

On the other hand, a protective terminal PT is further connected between the resistor R3 and the capacitor C3 or between the capacitor C5 and the resistor R3. This protective stage PT is electrically connected to the negative pack power supply stage P- when connected to a predetermined charger or external set. That is, the protection stage PT is in the ground state, thereby applying a low signal to the gate of the control switch 140 (that is, the gate of the field effect transistor), whereby the control switch 140 is in an on state. Becomes Of course, when the protection stage PT is in an open state (ie, the battery pack 100 is connected to an unspecified charger, an external set, or is disconnected from the charger, the external set), When the high signal is applied to the gate of the control switch 140 by the charging voltage, the control switch 140 is turned off. Therefore, even when the pack power stages P + and P- are overcharged, reverse charged, or shorted in this state, the power of the bare cell 110 is not supplied to the pack power stages P + and P-. Thus, the safety and reliability of the battery pack 100 is increased.

In addition, although the protection stage PT has been described as a configuration in which the negative electrode pack power supply terminal P- is in direct mechanical contact, in addition to such a configuration, it is also possible to be configured to be electrically connected by a bipolar transistor or a field effect transistor.

Furthermore, although the control switch 140 has been described as a configuration in which the protection stage PT is turned on only in contact with the negative electrode pack power supply terminal P-, a separate electronic circuit is provided in the charger or the external set. It is also possible to configure such that the control switch directly on, off.

The operation of the battery pack 100 according to the present invention having such a configuration will be described with reference to FIGS. 5 and 6 along with FIG. 4 as follows.

First, the operation when the protection stage PT of the battery pack 100 is opened will be described. That is, the protection stage PT of the battery pack 100 is not coupled to a predetermined charger or external set, or is coupled to an unspecified charger or external set. Here, the meaning that the battery pack 100 is coupled to the designated charger or the external set means that the protection stage PT and the negative electrode pack power supply stage P- are connected to each other, but in other cases, the protection stage (PT) and negative pack power terminal (P-) are all separated.

When the protection stage PT is opened in this manner, the control capacitor C3 is charged by the voltage of the bare cell 110. That is, the anode voltage is applied to one side of the control capacitor C3 through the parasitic diode D3 formed in the second control switch 142 (that is, the field effect transistor) of the control switch 140, and the bare cell 110 is applied. Negative voltage is applied to the other side of the control capacitor C3 through the negative cell power supply terminal B− and the charge / discharge switch 130 of FIG. 3), so that the control capacitor C3 is charged to a predetermined voltage. Accordingly, a high voltage is applied to the gate of the control switch 140 (that is, the gate of the field effect transistor), thereby turning off. That is, a high voltage is applied to the gate of the p-channel field effect transistor, thereby turning off.

Therefore, even when overcharge, overdischarge, short, or the like is performed in the pack power stages P + and P- in this state, the bare cell 110 and the positive electrode pack power stage P + are open, There is no effect on the bare cell 110. In addition, the parasitic diodes D3 and D4 provided in the control switch 140 also have a current flow through the diodes D3 and D4 because the cathodes are connected to each other.

On the other hand, the operation when the protective terminal PT of the battery pack 100 is connected to the negative electrode pack power supply terminal P- will be described. That is, the protection stage PT of the battery pack 100 is coupled to a predetermined charger or an external set, whereby the protection stage PT and the negative electrode pack power supply stage P- are mechanically inside the charger or the external set. Or a state in which circuits are connected to each other.

In this way, when the protective end PT is connected to the negative electrode pack power supply terminal P-, the control capacitor C3 is discharged. Accordingly, a low voltage is applied to the gate of the control switch 140 (that is, the gate of the field effect transistor), thereby turning on. That is, the low voltage is applied to the gate of the p-channel field effect transistor, thereby turning on.

Therefore, in this state, a current flows through the positive electrode pack power supply terminal P +, the control switch 140, the bare cell 110, the charge / discharge switch 130, and the negative electrode pack power supply terminal P- during charging, and is bare when discharging. Current flows into the cell 110, the control switch 140, the positive electrode pack power supply terminal P +, the negative electrode pack power supply terminal P−, and the charge / discharge switch 130. That is, the bare cell 110 is normally charged and discharged.

Meanwhile, the overcharge / discharge control state of the bare cell 110 in the state where the control switch 140 is turned on will be described below.

First, when the overcharge voltage is applied, the protection circuit 120 detects the overcharge voltage of the bare cell 110 using the VDD terminal and the VSS terminal connected in parallel to the bare cell 110. As such, when the bare cell 110 is in the overcharge voltage state, the protection circuit unit 120 applies a low signal to the gate of the charge switch 131 (that is, the field effect transistor) of the charge / discharge switch 130 to turn it off. Allow the overcharge to stop. In addition, during overcharge current, the protection circuit 120 detects the overcharge current by using the VM terminal and the VSS terminal connected to the charge / discharge switch 130 via the resistor R1. Of course, when the overcharge current is in this manner, the protection circuit unit 120 turns off the overcharge current state by applying a low signal to the gate of the charge switch 131 of the charge / discharge switch 130.

Of course, when the discharge state in the overcharge state (that is, when the external set is connected to the pack power supply terminals (P +, P-)), since the parasitic diode (D1) is formed in the charge switch 131, the normal discharge is It is possible.

Subsequently, the protection circuit unit 120 detects the overdischarge voltage of the bare cell 110 by using the VDD terminal and the VSS terminal connected in parallel to the bare cell 110 at the over discharge voltage. As such, when the bare cell 110 is in the over-discharge voltage state, the protection circuit unit 120 applies a low signal to the gate of the discharge switch 132 (that is, the field effect transistor) of the charge / discharge switch 130 to turn it off. In this case, the overdischarge state is stopped. In addition, during the over-discharge current (or an external short), the protection circuit unit 120 detects the over-discharge current by using the VM terminal and the VSS terminal connected to the charge / discharge switch 130 via the resistor R1. Of course, when the over-discharge current is in this manner, the protection circuit unit 120 turns off the over-discharge state by applying a low signal to the gate of the discharge switch 132 of the charge / discharge switch 130.

Of course, when the charging state is in the over-discharge state (that is, when the charger is connected to the pack power terminals P + and P-), since the parasitic diode D2 is formed in the discharge switch 132, normal charging is performed. It is possible.

As described above, in the present invention, the control switch is turned on only when the battery pack is connected to a predetermined charger or an external set, thereby enabling a state of charge and discharge.

Therefore, the battery pack is connected to an unspecified charger or external set, or the charge and discharge of the bare cell at the time of artificial overcharge, reverse charge, and short-circuit are blocked at the source, thereby increasing safety and reliability.

Of course, when the battery pack is connected to a designated charger or an external set, the present invention enables normal charge / discharge operation, and thus the protection circuit unit and the charge / discharge switch control the charge / discharge state.

What has been described above is only one embodiment for carrying out the battery pack according to the present invention, the present invention is not limited to the above-described embodiment, the scope of the present invention as claimed in the claims below Without this, anyone skilled in the art to which the present invention pertains will have the technical spirit of the present invention to the extent that various modifications can be made.

Claims (14)

Bare cells connected in parallel to the pack power supply; A protection circuit unit connected to the bare cells in parallel to sense a charge / discharge voltage and a current, and control the same according to a predetermined order; A charge / discharge switch connected in series between the pack power supply terminal and the bare cell and controlling charge / discharge of the bare cell under control of the protection circuit unit; And, And a control switch that is connected in series between the pack power supply terminal and the bare cell and is turned on only when the pack power supply terminal is connected to a designated charger or an external set. The method of claim 1, wherein the bare cell includes a positive cell power supply terminal and a negative cell power supply terminal, the pack power supply terminal comprises a positive electrode pack power supply terminal and a negative electrode pack power supply terminal, the charge and discharge switch is a negative cell power supply terminal and a negative electrode pack And a control switch connected between a positive cell power terminal and a negative electrode pack power terminal. The battery pack according to claim 1, wherein the charge / discharge switch is composed of a charge control field effect transistor that is turned off when overcharged and has a parasitic diode, and a field effect transistor that is turned off during over discharge and has a parasitic diode. The battery pack as claimed in claim 1, wherein the control switch is at least one field effect transistor. The battery pack as claimed in claim 1, wherein the control switch is at least one field effect transistor having a parasitic diode. The method of claim 1, wherein the control switch At least one field effect transistor having a source and a drain connected in series to a cathode cell power supply terminal and a cathode pack power supply terminal of the bare cell; A control capacitor connected between the gate of the field effect transistor and the cathode pack power supply terminal; And, And a protective terminal connected between the gate and the control capacitor, the protective terminal being connected to the negative pack power supply terminal when the battery pack is coupled to a designated charger or an external set. 7. The battery pack as claimed in claim 6, wherein the protection stage is electrically connected to the negative pack power supply terminal inside the charger or the external set. 7. The field effect transistor of claim 6, wherein when the protection stage is open, the gate is held in a high state by a voltage charged in the control capacitor, and the field effect transistor is turned off. And the control capacitor is discharged when the protective terminal is connected to the negative electrode pack power supply terminal, so that the gate is turned on while the gate is kept low. 7. The battery pack as claimed in claim 6, wherein a capacitor for preventing power fluctuation is further connected between the source and the drain of the field effect transistor. The battery pack as claimed in claim 6, wherein a capacitor for preventing power fluctuation is further connected between the drain and the protection terminal of the field effect transistor. The battery pack as claimed in claim 6, wherein an antistatic resistor is further connected between the gate of the field effect transistor and the control capacitor. The battery pack according to claim 1, wherein one end of the protection circuit unit is connected to one side of the charge / discharge switch, and the other end of the protection circuit unit is connected to the other side of the charge / discharge switch through an overcurrent detection resistor. 2. The method of claim 1, wherein an antistatic resistor and a power fluctuation preventing capacitor are connected between the positive cell power source terminal and the negative cell power supply terminal of the bare cell, and the voltage detection of the bare cell is performed between the antistatic resistance and the power source fluctuation preventing capacitor. Battery pack, characterized in that for connecting one side of the protection circuit. The battery pack as claimed in claim 1, wherein a capacitor for preventing power fluctuation is further connected to both ends of the charge / discharge switch.

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