KR20100133560A - Pcm with novel structure and battery pack including the same - Google Patents

Abstract

PURPOSE: A protection circuit module is provided to precisely perform detection for current value and high temperature and to minimize the number of components. CONSTITUTION: A protection circuit module(102) for protecting a secondary battery from overcharging, overdischarging, charge excess current and discharge excess current includes: a protection integrated circuit(212) for accumulating an over charge detection circuit, an over discharge detection circuit, a charge overcurrent detection circuit, and a discharge overcurrent detection circuit; a FET device(230) for recharge control which is off when overcharging or charge excess current is detected; a FET device(220) for discharge control; and an NTC thermistor(240).

Description

Novel Structure and Battery Pack Including the Same}

The present invention relates to a protection circuit module having a novel structure and a battery pack including the same, and more particularly, a protection integrated circuit module that protects a secondary battery from overcharge, overdischarge, charge overcurrent and discharge overcurrent. And a charge control FET device, a discharge control FET device, and a negative characteristic thermistor, wherein the protection integrated circuit includes a sensitivity resistor device for accurately sensing current; A heat sensing element for sensing heat and converting the heat into an electrical signal; And at least one selected from the group consisting of an input resistor (first resistor) for supplying power to the protection integrated circuit and a current limiting resistor (second resistor) for protecting the internal logic of the protection integrated circuit. It relates to a circuit module and a battery pack including the same.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, a lot of researches on secondary batteries that can meet various needs have been conducted.

Representatively, there is a high demand for lithium secondary batteries with high energy density, discharge voltage, and output stability in terms of battery material, and in the form of a thin film, they can be applied to products such as mobile phones and are stacked with high integration. There is a high demand for square cells and pouch cells that can also be used as batteries.

However, while lithium secondary batteries have the above advantages, they have a fundamental problem of low safety. For example, when the battery is overcharged, the electrolyte decomposition reaction at the electrode is promoted to generate a flammable gas, and the overcurrent caused by various internal short circuits increases the temperature of the battery, causing decomposition of the battery components. . Due to such overcharge and overcurrent, the battery is easy to ignite, and in some cases, may explode. In addition, even if it is not an overcurrent, the temperature rise due to other causes causes the above problems. Therefore, the lithium secondary battery has a variety of safety devices are built in to solve this problem.

Representative examples of such safety devices include PTC, fuses, bimetals, and the like. Among them, PTC is a safety device that cuts off the current due to a large increase in resistance due to an overcurrent or the like, and a fuse is a safety device that cuts off when the temperature rises due to an overcurrent or the like and cuts off the current. In addition, bimetal is a safety device that blocks an electrical connection due to a difference in thermal expansion rate when a temperature rises.

All of these safety devices are effective in solving problems caused by overcurrent, but do not solve problems caused by overvoltage such as overcharge and overdischarge. The over-discharge of the battery does not cause safety problems, but causes the collapse of the negative electrode material, thereby causing a significant decrease in the performance of the battery. Therefore, in order to eliminate the overvoltage of the battery, a protection circuit module (PCM) is generally additionally installed in the secondary battery.

1 is an exploded perspective view of one exemplary battery pack having a structure in which a PCM is mounted on a secondary battery according to the related art.

Referring to FIG. 1, the battery pack 100 includes a PTC block 201 on top of a secondary battery (battery cell 110) in which an electrode assembly (not shown) including an anode, a cathode, and a separator is embedded together with an electrolyte. And the PCM substrate 202 are electrically connected to and mounted by the nickel plates 120, 122, 124, and 126, and the top cap 300 of the battery insulating material is mounted thereon. After the assembly of the battery pack 100 is completed, the external input / output terminals 204 and 206 formed on the top of the PCM substrate 202 are moved outwardly through the openings 304 and 306 of the top cap 300. Exposed. Accordingly, since the secondary battery 110 is energized through the PTC block 201 and the PCM substrate 202, the overcurrent and the overvoltage are controlled by these safety elements 201 and 202.

2 is an exemplary circuit diagram showing the structure of a PCM in a battery pack.

Referring to FIG. 2, the PCM 200 includes active devices such as the protection integrated circuit 210 and the FET devices 220 and 230, and includes an NTC thermistor 240.

The PTC element 260 is connected to the negative electrode side of the secondary battery 110, and external input / output electrode terminals V + and V− are connected to both ends.

Referring to these operations, when the voltage of the secondary battery 110 reaches the overcharge protection voltage, the protection integrated circuit 210 turns off the charge control FET device 230 to cut off the current. On the contrary, when the voltage of the secondary battery 110 reaches the over-discharge prevention voltage, the protection integrated circuit 210 turns off the discharge control FET device 220 to cut off the current. When the detection voltage falls below the overcharge protection voltage or rises above the overdischarge prevention voltage, the protection integrated circuit 210 may switch the charge control FET device 230 or the discharge control FET device 220 back to an on state. Energize. In the case of overcurrent, the protection integrated circuit 210 turns off the discharge control FET device 220 to cut off the current. In addition, when the current increases by more than a predetermined value and the temperature rises, the PTC element 260 is cut off to ensure safety.

However, the configuration of such a PCM has the following problems.

First, a method of detecting a current in the protection integrated circuit 210 is a method of sensing the difference between the voltage applied to the on-resistance (Rdson) values across the charge control FET device 230 and the discharge control FET device 220. . However, such a current sensing method has a problem in that the detection force is much lowered compared to a method of detecting a current value by a voltage using a sense resistor which is a current sensing technology.

Second, in order to protect the battery pack against high temperature, a method of using the PTC device 260 or the NTC thermistor 240 to recognize the heat information in the mobile phone device to prevent charging is used. However, such a high temperature detection method has a problem that can not accurately sense the temperature.

Third, the protection integrated circuits used in current battery packs use an input resistor for supplying power to the protection integrated circuit and a current limiting resistor for protecting the internal logic of the protection integrated circuit. However, these resistors increase the number of parts of the PCM, so that the overall volume of the PCM is problematic.

Therefore, in order to solve the above problems, the sensitivity resistor element, the thermal sensing element, or the input resistor and the current limiting resistor are configured in the protection integrated circuit in one package to more accurately detect the current value and the high temperature and There is a great need for a technology related to a protection circuit module and a battery pack including the same.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

After in-depth research and various experiments, the inventors have developed a sensitivity package, a thermal sensing element, or an input resistor and a current limiting resistor in a single package in a protection integrated circuit to detect current value and high temperature. It has been found that the precision and the number of parts can be minimized and the present invention has been completed.

Accordingly, the protection circuit module according to the present invention is a protection circuit module that protects the secondary battery from overcharge, overdischarge, charge overcurrent and discharge overcurrent, and includes an overcharge detection circuit, an overdischarge detection circuit, a charge overcurrent detection circuit, and a discharge overcurrent detection circuit. A protection integrated circuit (IC) integrated therein; A charge control FET element that is turned off when overcharge is detected by the overcharge detection circuit or when charge overcurrent is detected by the charge overcurrent detection circuit; A discharge control FET element which is turned off when over discharge is detected by the over discharge detection circuit or when discharge over current is detected by the discharge over current detection circuit; And a negative characteristic thermistor (NTC Thermisor) whose resistance value changes with temperature change, wherein the protection integrated circuit includes a sensitivity resistor that senses current accurately; A thermal sensing element for sensing heat and converting it into an electrical signal; And an input resistor (first resistor) for supplying power to the protection integrated circuit and a current limiting resistor (second resistor) for protecting the internal logic of the protection integrated circuit. Consists of.

Therefore, in the protection circuit module of the present invention, when the protection integrated circuit includes a sense resistor that senses current accurately, overcurrent can be detected to a more precise unit.

In addition, when the protection integrated circuit includes a thermal sensing element that senses heat and converts it into an electrical signal, the detection force against high temperature may be further improved.

Moreover, if the protection integrated circuit includes an input resistor (first resistor) for supplying power and a current limiting resistor (second resistor) for protecting the internal logic of the protection integrated circuit, the number of components included in the PCM. You can save more than two.

One or more of these sensitivity resistors, thermal sensing elements, input resistors (first resistors), current limiting resistors (second resistors), and the like may be included in the protection integrated circuit. It is a novel structure not disclosed in the prior art.

The sensitivity resistive element may detect an overcurrent up to several hundred mA, and specifically, may detect an overcurrent in a range of -200 mA to +200 mA.

Therefore, the protective circuit module including such a sensitivity resistor element is preferable because it can improve the detection force in the conventional -1 A to +1 A range up to several hundred mA units.

The heat sensing device performs a function of blocking the charge control FET device and the discharge control FET device at a predetermined temperature. As a specific example, the predetermined temperature may be 80 to 90 degrees Celsius.

Therefore, the protection circuit module including the heat sensing sensing element has an advantage of not increasing the volume of the protection circuit module while ensuring the detection force against high temperature.

Meanwhile, the method of including the sensitivity resistor element, the thermal sensing element, the first resistor, and the second resistor in the protection circuit module may be mounted on the protection circuit board or integrated in a package in the protection integrated circuit. In the latter case, it is preferable to increase the total volume of the protection circuit module.

As one example, the sensitivity resistive element may be configured to be integrated into a protection integrated circuit in one package, and in this case, it is desirable to precisely secure a desired current detection capability while not increasing the volume of the protection circuit module. Do.

As another example, the heat sensing sensing element may be configured to be integrated into a protection integrated circuit in one package. In this case, since the sensing force for a desired high temperature is easily secured, the volume of the protection circuit module is not increased. desirable.

In some cases, the first resistor and the second resistor may be integrated into the protection integrated circuit in a single package, and in this case, two parts of the protection circuit module may be reduced, thus greatly improving design optimization. It works.

The secondary battery according to the present invention is not particularly limited as long as it is a charge / discharge battery requiring safety, and may be preferably used for a lithium secondary battery. Lithium secondary batteries may be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries according to the type of battery components. Any lithium secondary battery may be a battery that is charged and discharged by reversible occlusion and desorption of lithium ions. .

The present invention also provides a battery pack including a protection circuit module, a secondary battery for supplying power, and a PTC element whose resistance increases rapidly at a predetermined temperature.

In this case, the battery pack may be used as a power source for various electronic devices such as a mobile phone and a notebook computer. Preferably, the battery pack may be used as a power source for a mobile phone.

Hereinafter, the content of the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

3 through 5 illustrate circuit diagrams of a battery pack according to various embodiments of the present disclosure.

First, referring to FIG. 3, the battery pack 102 includes a secondary battery 110 for supplying power, a protection circuit module 202 connected to a positive electrode and an external positive / output terminal of the secondary battery 110, and a predetermined temperature. It is composed of a PTC element 260 that the resistance increases rapidly and is connected to the negative electrode of the secondary battery.

The protection circuit module 202 includes a protection integrated circuit 212, a charge control FET device 230 and a PTC device connected to the external negative input / output terminal V- of the secondary battery 110 and the protection integrated circuit 212. 260, a discharge control FET device 220 connected to the protection integrated circuit 212, and a negative characteristic thermistor 240 whose resistance value changes extremely with temperature change.

The protection integrated circuit 212 integrates an overcharge detection circuit, an overdischarge detection circuit, a charge overcurrent detection circuit, a discharge overcurrent detection circuit, and a sensitivity resistor element for accurately sensing current in one package. That is, since the protection integrated circuit 212 includes a sensitivity resistor, the current is accurately detected from -200 mA to +200 mA.

Further, the charge control FET element 230 is turned off when overcharge is detected by the overcharge detection circuit of the protection integrated circuit 212 or when charge overcurrent is detected by the charge overcurrent detection circuit of the protection integrated circuit 212. OFF). The discharge control FET element 220 is turned off when over discharge is detected by the over discharge detection circuit of the protection integrated circuit 212 or when discharge over current is detected by the discharge over current detection circuit of the protection integrated circuit 212. .

The secondary battery 110 is a battery cell capable of charge / discharge, which is sealed inside the battery case in a state in which an electrode assembly having a cathode / separator / cathode structure is impregnated with a lithium electrolyte. Such an electrode assembly has a jelly-roll structure (winding type) in which a long sheet type positive electrode and a negative electrode having active materials coated on both surfaces are separated with a separator, and a plurality of positive and negative electrodes having a predetermined size coated with active materials on both sides. Stacked (stacked) structures in which dogs are sequentially stacked with a separator interposed therebetween are common.

As the secondary battery 110, both cylindrical and square electrodes in which an electrode assembly is built in a battery case of a metal can and pouch type battery cells in which an electrode assembly is embedded in a battery case of an aluminum laminate sheet may be used. have. The secondary battery 110 may have a structure in which two or more battery cells are connected in series and / or in parallel.

The PTC device 260 is a polymer composite having a property in which a resistance value increases nonlinearly by heat, and generally has a structure in which carbon powder is dispersed in a polymer matrix. The PTC element 260 is connected to the negative electrode of the secondary battery 110 and is connected to the external input / output negative electrode terminal V-. Therefore, when an overcurrent flows from the secondary battery 110 during the discharging process of the battery pack 102, the overall temperature of the circuit increases, and at this time, the resistance of the PTC element 260 increases to block the current. When the temperature is lowered to an appropriate level again, the resistance value of the PTC element 260 is also lowered so that electricity is supplied again.

Next, referring to FIG. 4, the description is the same as that of FIG. 3 except that the sensitivity resistor element 250 is electrically connected between the protection integrated circuit 210 and the external cathode input / output terminal V−. Will be omitted.

3 and 4, the sensitivity resistive element 250 is integrated in one package in the protection integrated circuit 212 as in the structure of FIG. 3 to form a chip, or as in the structure of FIG. 4. The circuit inside the module may be formed between the protection integrated circuit 210 and the external negative input / output terminal V−.

Referring to FIG. 5, the heat sensing sensing element is integrated in a single package in the protection integrated circuit 214 to shut off the charge control FET device 230 and the discharge control FET device 220 at a temperature of 80 to 90 degrees Celsius. It performs the function.

6 schematically shows another exemplary circuit diagram of a structure in which a PCM is included in a conventional battery pack.

Referring to FIG. 6, the battery pack 104 includes a capacitor 270 as a passive element, a protection integrated circuit 216, a charge control FET element 230, and a discharge control FET in a secondary battery 110 capable of charging and discharging. It is made of a structure in which the device 220 is connected. In addition, the protection integrated circuit 216 includes a first resistor 280 that is an input resistor for supplying power to the protection integrated circuit 216 and a second resistor 282 that is a current limiting resistor for protecting the internal logic of the protection integrated circuit. ) And external input / output electrode terminals (V +, V-).

The capacitor 270 has a capacity of 0.1 μF and is adjacent to the first resistor 280, and is connected in parallel with the secondary battery 110.

7 is a circuit diagram of a battery pack according to another embodiment of the present invention.

Referring to FIG. 7 together with FIG. 6, the first resistor 280 and the second resistor 282 are integrated in the protection integrated circuit 218 in one package, thereby reducing the number of components of the protection circuit module from six to four. Reduced to dogs.

As described above, the protection circuit module according to the present invention comprises a sensitivity resistor element, a heat sensing sensing element, or an input resistor and a current limiting resistor in one package in a protection integrated circuit to more accurately detect current values and high temperature. Performance and the number of parts can be minimized. In addition, since the overcurrent and the overvoltage of the secondary battery can be precisely controlled to ensure the safety of the battery, the secondary battery pack can be manufactured at low cost.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

1 is an exploded perspective view of one exemplary battery pack with a structure in which a PCM is mounted to a secondary battery according to the prior art;

2 is one exemplary circuit diagram of a structure in which a PCM is included in a conventional battery pack;

3 to 5 are circuit diagrams of a battery pack according to various embodiments of the present disclosure;

6 is another exemplary circuit diagram of a structure in which a PCM is included in a conventional battery pack;

7 is a circuit diagram of a battery pack according to another embodiment of the present invention.

Claims (10)

A protection circuit module that protects a secondary battery from overcharge, overdischarge, charge overcurrent, and discharge overcurrent, A protection IC that integrates an overcharge detection circuit, an overdischarge detection circuit, a charge overcurrent detection circuit, and a discharge overcurrent detection circuit; A charge control FET element that is turned off when overcharge is detected by the overcharge detection circuit or when charge overcurrent is detected by the charge overcurrent detection circuit; A discharge control FET element which is turned off when over discharge is detected by the over discharge detection circuit or when discharge over current is detected by the discharge over current detection circuit; And Includes a NTC Thermistor whose resistance changes with temperature. The protection integrated circuit includes a sensitivity resistor (Sense Resistor) for accurately sensing the current; A thermal sensing element for sensing heat and converting it into an electrical signal; And at least one selected from the group consisting of an input resistor (first resistor) for supplying power to the protection integrated circuit and a current limiting resistor (second resistor) for protecting the internal logic of the protection integrated circuit. Protective circuit module characterized in that. The protection circuit module according to claim 1, wherein the sensitivity resistor detects overcurrent up to several hundred mA. The protection circuit module according to claim 1, wherein the heat sensing sensing element performs a function of blocking the charge control FET device and the discharge control FET device at a predetermined temperature. 4. The protection circuit module of claim 3, wherein the predetermined temperature is 80 to 90 degrees Celsius. The protection circuit module according to claim 1, wherein the sensitivity resistor element is integrated in a protection integrated circuit in one package. The protection circuit module of claim 1, wherein the heat sensing sensing element is integrated in a protection integrated circuit in one package. The protection circuit module of claim 1, wherein the first resistor and the second resistor are integrated in a protection integrated circuit in one package. The protective circuit module of claim 1, wherein the secondary battery is a lithium secondary battery. A battery pack comprising a protection circuit module according to claim 1, a secondary battery for supplying power, and a PTC element having a rapid increase in resistance at a predetermined temperature. The battery pack as claimed in claim 9, wherein the battery pack is used as a power source for a mobile phone.

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