Apparatus and method for managing battery pack

The present invention discloses an apparatus and method for managing a battery pack, which can rapidly and accurately diagnose the coupling state of a bus bar to battery modules in the battery pack. In accordance with the present invention, provided is an apparatus for managing a battery pack having a plurality of battery modules and a bus bar coupled between the battery modules to electrically connect the battery modules, the apparatus comprising a coupling detection unit for detecting the coupling state of the bus bar to the battery modules; and a controlling unit for determining whether the coupling state of the bus bar has a defect on the basis of the coupling state detected by the coupling detection unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No. PCT/KR2011/009953 filed on Dec. 21, 2011, which claims priority to Korean Patent Application No. 10-2011-0001688 filed in the Republic of Korea on Jan. 7, 2011, the entire contents disclosed in the specification and drawings of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a technology for managing a battery pack, and more particularly, to an apparatus and method for managing the battery pack which can detect whether or not there is a defect in the coupling state of a bus bar coupled between a plurality of battery modules comprised in the battery pack.

BACKGROUND ART

Recently, with the rapid increase in the demand for portable electronic products such as notebooks, video cameras and cellular phones and the development of energy storage batteries, robots, satellites, etc. under active progress, numerous studies are being made on high-performance secondary batteries capable of being repeatedly charged and discharged.

Currently, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries or the like are commercially available as secondary batteries. Among these, lithium secondary batteries are at the center of interest because they hardly have memory effects and can be freely charged or discharged in comparison with nickel-based secondary batteries. Advantageously, the lithium secondary batteries also exhibit very low self-discharge rate and high energy density.

Meanwhile, with the gradual exhaustion of carbon energies and the increased interest in the environment, the demands for hybrid and electric vehicles are increasing all around the world, including U.S.A, Europe, Japan and Korea. The hybrid or electric vehicles obtain driving force by means of energy charged and discharged in a battery pack, thereby eliminating or reducing an exhausted pollutant while ensuring excellent fuel efficiency compared to only engine-driven vehicles. Thus, the hybrid or electric vehicles better appeal to many consumers. Accordingly, the battery which is the most fundamental part in such hybrid or electric vehicles is the focus of many interests and studies.

The battery pack, particularly the battery pack used in electric vehicles has a plurality of battery modules to output high voltage, and the battery modules are connected by a connecting member called a bus bar. The bus bar should be strongly coupled with the battery modules therebetween so as to carry out electrical connection between the battery modules. Accordingly, the bus bar is coupled to the battery modules by a connecting member such as a bolt, nut or the like, and its coupling state is securely sustained.

However, since battery packs are generally used in devices and apparatuses that have frequent movement, there is a chance that the coupling state of the bus bar to the battery modules in the battery pack will loosen. For example, in the case of an electric vehicle in operation, the bus bar can loosen from the battery modules which will weaken the coupling state of the bus bar to the battery modules due to the impact and vibration applied to the battery pack. Furthermore, the loose coupling state of the bus bar only worsens over time, and unless artificially repaired, will not get any better.

Meanwhile, as the coupling state of the bus bar to the battery modules in the battery pack worsens, the resistance of the bus bar may increase causing the energy loss of the battery pack and heat generation, thereby leading to the overall temperature rise of the battery pack. This temperature rise of the battery pack may cause the performance degradation of the battery pack, as well as, in a severe case, the ignition or explosion thereof, which may induce a great problem on the stability of the battery pack.

DISCLOSURE

Technical Problem

The present invention is designed to solve the problems of the prior art, and therefore, it is an aspect of the present invention to provide an apparatus and method for managing a battery pack, which can rapidly and accurately detect the coupling state of a bus bar to battery modules in the battery pack.

Additional aspects and advantages will be apparent from the embodiments of the present invention. The aspects and advantages of the invention may be realized by means of instrumentalities and combinations particularly pointed out in the appended claims.

Technical Solution

In order to accomplish the above object, the present invention provides an apparatus for managing a battery pack having a plurality of battery modules and a bus bar coupled between the battery modules to electrically connect the battery modules, the apparatus comprising a coupling detection unit for detecting the coupling state of the bus bar to the battery modules; and a controlling unit for determining whether the coupling state of the bus bar has a defect on the basis of the coupling state detected by the coupling detection unit.

Preferably, the coupling detection unit comprises a pressure sensor.

Also, the apparatus for managing a battery pack according to the present invention may further comprise a warning unit for providing information on the coupling defect of the bus bar, which is determined by the controlling unit, to a user.

Preferably, the controlling unit comprises a battery management system (BMS).

In addition, in order to accomplish the above object, the present invention provides a battery pack comprising the above battery pack managing apparatus.

Also, in order to accomplish the above object, the present invention provides a vehicle comprising the above battery pack managing apparatus.

Further, in order to accomplish the above object, the present invention provides a method for managing a battery pack having a plurality of battery modules and a bus bar coupled between the battery modules to electrically connect the battery modules, which comprises the steps of detecting the coupling state of the bus bar and determining whether the coupling state of the bus bar has a defect on the basis of the coupling state of the bus bar detected.

Preferably, the coupling state of the bus bar is detected by a pressure sensor.

In addition, the method for managing a battery pack according to the present invention may further comprise the step of informing a user that the coupling state of the bus bar has a defect, when the coupling state of the bus bar is determined to have a defect.

Furthermore, the determination whether the coupling state of the bus bar has a defect may be conducted by a BMS.

Advantageous Effects

In accordance with the present invention, the coupling state of a bus bar by which a plurality of battery modules comprised in a battery pack are connected with each other can be rapidly and accurately determined. Particularly, in the case of a battery pack used in electric vehicles, the bus bar may weaken due to a lot of impact and vibration applied to the battery pack and exposure to rapid changes in temperature. However, according to the present invention, a defect of the coupling state of a bus bar can be easily detected.

Accordingly, a user can rapidly and accurately check a suitable time for repairing or exchanging the bus bar from the coupling state information of the bus bar and take suitable action.

Thus, the apparatus and method of the present invention can be used to prevent energy loss and heat generation in a battery pack due to the coupling defect of the bus bar, as well as the deformation of the bus bar or the performance degradation or explosion of the battery pack, which results from the heat generation due to the coupling defect of the bus bar.

Particularly, in accordance with one embodiment of the present invention, when the bus bar has a coupling defect, the flow of an electric current can be interrupted to stop the use of the battery pack, thereby enhancing the stability of the battery pack.

BEST MODE

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

FIG. 1is a block diagram schematically showing a functional configuration of an apparatus for managing a battery pack having battery modules10and a bus bar20according to one embodiment of the present invention. Referring toFIG. 1, the battery pack managing apparatus of the present invention comprises a coupling detection unit110and a controlling unit120.

The battery pack may comprise a plurality of battery modules10, particularly in the case of a middle- or large-sized battery pack requiring high voltage, such as a battery pack for electric vehicles, even more battery modules10are comprised. Each battery module10has a positive and negative electrode socket for the input/output of electric current.

The battery modules10are coupled with a bus bar20positioned therebetween. The battery modules10and the bus bar20may be coupled by various means, e.g., a coupling member such as bolts and nuts.

The bus bar20is a component for allowing the battery modules10to electrically connect with each other, and so may be made of materials having good electrical conductivity such as copper. The bus bar20may be made in various forms depending on the inner structure of the battery pack, the connection state of the battery modules, etc. For example, the bus bar20may be in the form of a metal plate or a wire. Thus, the bus bar20used herein means a component for allowing a plurality of the battery modules10to electrically connect with each other by being coupled with each of the battery modules10, and it is not limited to its form and denomination.

The coupling detection unit110detects the coupling state of the battery modules10and the bus bar20. That is, whether the bus bar20is well-coupled to the battery modules10or whether it has loosened therefrom. The detection by the coupling detection unit110may be conducted in various manners.

Preferably, the coupling detection unit110may comprise a pressure sensor. Specifically, the coupling detection unit110can detect the coupling state of the bus bar20to the battery modules10through the pressure sensor.

FIG. 2is a perspective view schematically showing a separated-configuration for detecting the coupling state of a bus bar by a pressure sensor according to one embodiment of the present invention, andFIG. 3is a perspective view schematically showing a combined-configuration ofFIG. 2. Also,FIG. 4is a view seeing the coupling region of the bus bar shown inFIG. 3from top to bottom of the battery module.

Referring toFIGS. 2 to 4, the bus bar20is coupled with two battery modules therebetween, and thus the battery modules10are electrically connected through the bus bar20. At this time, the battery modules10may have bold-shaped electrode sockets11by which the bus bar20is coupled together with nuts12. However, the coupling of the battery modules10and the bus bar20may be conducted in various forms, and the present invention is not limited to any specific coupling form thereof.

Meanwhile, a pressure sensor111may be provided between the bus bar20and the battery modules10. The pressure sensor111may function as a coupling detection unit110for detecting the coupling state of the bus bar20to the battery modules10. As shown in the drawings, the bus bar20is coupled with the battery modules10by means of a coupling member such as nuts, and the pressure sensor111may be applied with some extent of pressure in a normal state. However, if any variation on the coupling state of the bus bar20to the battery modules10occurs, the pressure sensor111may undergo the change of the pressure applied thereto. For example, in the embodiments ofFIGS. 3 and 4, when the nuts12become loose, the pressure applied to the pressure sensor111is reduced and thus the pressure detected thereby is also decreased. Thus, the pressure sensor111provided in the coupling region between the bus bar20and the battery modules10may measure a pressure to detect any variation on the coupling state of the bus bar20. At this time, it is preferred that the pressure sensor111is a thin film-type pressure sensor having a thin thickness. As shown in drawings, the pressure sensor111may be interposed between the bus bar20and the battery modules10. Therefore, if the thickness of the pressure sensor111is too thick, this may restrict the bus bar20to tightly couple to the battery modules10. Accordingly, it is preferred that the pressure sensor111has a thin-film type as thin as paper or an ultra thin film-type. The present invention is, however, not limited to any specific type of the pressure sensor111, and the various types of the pressure sensor may be used.

Preferably, the coupling detection unit110may also comprise a voltage sensor. That is, the coupling detection unit110may measure the voltage change on both ends of the bus bar20through the voltage sensor to detect the coupling state of the bus bar20.

FIG. 5schematically shows a configuration for detecting the coupling state of a bus bar20by a voltage sensor112according to one embodiment of the present invention.

Referring toFIG. 5, the voltage sensor112is provided on both ends of the bus bar20coupled between two battery modules10, thereby being capable of measuring the current of both ends of the bus bar20. In a normal state, the bus bar20has a constant resistance and current and it will most likely show no observable voltage change on both ends thereof. However, when the coupling state between the bus bar20and the battery modules10is loosened, for example, by means of loose nuts12, the resistance of the bus bar20may be increased. At this time, an increase in the resistance of the bus bar20means an increase in the voltage of both ends of the bus bar20since there will be no changes in the current flow of the bus bar20. Therefore, the voltage sensor112can detect the coupling state of the bus bar to the battery modules10by measuring the voltage of both ends of the bus bar20.

Meanwhile, the detection for the coupling state of the bus bar20by means of the coupling detection unit110may be continuously or discontinuously conducted. For example, the pressure sensor111may continuously or periodically detect a pressure applied from the bus bar20.

The controlling unit120determines the occurrence of a defect in the coupling state of the bus bar20on the basis of the results obtained by the coupling detection unit110, that is, any variation on the coupling state of the bus bar20which is detected by means of the coupling detection unit110.

Preferably, in the case that the coupling detection unit110is the pressure sensor111as shown inFIGS. 2 to 4, the controlling unit120may determine the occurrence of a defect in the coupling state of the bus bar20when a pressure detected by the pressure sensor111is lower than a reference pressure. Here, the reference pressure means a pressure value which can be detected by the pressure sensor111in the normal coupling state of the bus bar20to the battery modules20. At this time, like a battery of an electric vehicle, since impact and vibration may be applied to a battery pack to some extent, although there might not be any observable effects in the coupling state of the bus bar20, the pressure value detected by the pressure may change a bit. Accordingly, the reference pressure may have a value of a certain range, not a specific value.

For more specific consideration, assuming that the reference pressure for a comparison with a voltage detected by the pressure sensor111ranges from 10 to 30 kg/cm2, the controlling unit120may determine the coupling state of the bus bar to have no observable defect when the voltage detected by the pressure sensor111is from 10 to 30 kg/cm2. However, if the voltage detected by the pressure sensor111is lower than 10 kg/cm2, the lower limit of the reference pressure, the bus bar may be determined to have a coupling defect. The looseness of the bus bar20reduces a pressure applied to the pressure sensor111, so the controlling unit120may determine the coupling state of the bus bar to have a defect on the basis of the looseness.

Preferably, if the controlling unit120comprises a voltage sensor112as shown inFIG. 5, a defect occurrence in the coupling state of the bus bar20may be checked by a voltage detected by the voltage sensor112. That is, the controlling unit120can calculate the resistance of the bus bar20by using a voltage detected by the voltage sensor112and a current flowing through the bus bar20. At this time, the current flowing through the bus bar20may be separately measured through a current sensor, or may be a predetermined value. Then, if the calculated resistance is higher than a reference resistance, the controlling unit120may determine a defect in the coupling state of the bus bar by comparing the resistance calculated with the reference resistance.

For example, in the condition that the reference resistance ranges from 50 to 70Ω and a 10 A current flows in the bus bar, if the voltage of both ends of the bus bar20is detected to have a 600 V value by the voltage sensor112, the controlling unit120may calculate the resistance of the bus bar20to be 60Ω (600 V/10 A). Thus, since the resistance calculated of the bus bar20is within the range of the reference resistance value, the controlling unit120may determine no defect in the coupling state of the bus bar20to the battery modules10. However, if the voltage of both ends of the bus bar20is detected to have a 800 V value by the voltage sensor112, the controlling unit120may calculate the resistance of the bus bar20to be 80Ω (800 V/10 A). This resistance of the bus bar20is higher than the reference value, so the controlling unit120may determine a defect in the coupling state of the bus bar20. This is because the resistance of the bus bar20increases if the coupling of the bus bar20weakens and becomes loose.

Meanwhile, the controlling unit120may also determine whether the coupling state of the bus bar20has a defect by comparing the voltage itself of both ends of the bus bar20with a reference voltage, although the determination for a coupling defect of the bus bar20have been conducted by calculating the resistance of the bus bar20from the voltages of both ends of the bus bar20and then comparing the resistance calculated with a reference value in the embodiment described above. For example, in the condition that a 10 A current constantly flows in the bus bar20and a reference voltage ranges from 500 to 700 V, if a voltage measured in both ends of the bus bar20exceeds the range of the reference voltage, the controlling unit120may determine a defect in the coupling state of the bus bar20because the resistance change may be estimated on the basis of the voltage change in a constant current.

Such a controlling unit120, which determines whether the coupling state of the bus bar has a defect20on the basis of the variation of the coupling state detected by the coupling detection unit110, may comprise a battery management system (BMS). The term BMS used herein means a battery managing system provided in a battery pack to control overall charging/discharging operation of the battery. However, the present invention is not limited to such a means for carrying out the controlling unit120, and the controlling unit120may be constructed independent of the BMS.

Also, if the controlling unit120determines that the coupling state of the bus bar20has a defect, the charge/discharge current of the battery modules10may be interrupted to stop the use of the battery pack. If the battery pack is continuously used in the coupling defection state of the bus bar20, the battery pack may be subject to the performance degradation thereof due to heat generation and, in a severe case, the ignition or explosion thereof. Accordingly, the controlling unit120can interrupt the charge/discharge current of the battery modules10to stop the use of the battery pack so as to prevent the coupling defect of the bus bar20to undergo more severe problems. Here, the interruption of the charge/discharge current of the battery modules10may be conducted in various manners, for example, by melting a fuse positioned on the charging/discharging path of the battery pack or allowing a charging/discharging switch to be off.

Meanwhile, the use of the battery pack is stopped as described above, such a state information may be provided to a user before or after stopping the use of the battery pack.

Also, as shown inFIG. 1, the battery pack managing apparatus according to one embodiment of the present invention may further comprise a memory unit140.

The memory unit140may store all kinds of data necessary for conducting the functions of each component of the battery pack managing apparatus, i.e., a coupling detection unit110, a controlling unit120, etc. For example, the memory unit140may store data on a reference pressure if the coupling defect of the bus bar20is determined by the controlling unit120on the basis of a pressure detected by the pressure sensor111. Also, the memory unit140may store data on a reference voltage or a current flowing in the bus bar20if the coupling defect of the bus bar20is determined by the controlling unit120on the basis of a voltage detected by the voltage sensor112.

Also, the battery pack managing apparatus according to one embodiment of the present invention may further comprise a warning unit130.

The warning unit130informs a user of the coupling defect of the bus bar20when the coupling defect of the bus bar20is determined by the controlling unit120. For this information provision, the warning unit130may have a warning lamp, a display device such as a LCD monitor or a speaker. For example, in the case of the battery managing apparatus for vehicles, when there is a coupling defect of the bus bar20in the battery pack for vehicles, the warning unit130may inform a driver of the coupling defect of the bus bar20through a LCD monitor and a speaker equipped in a driving seat. Then, the driver can recognize a need for the maintenance, repair and exchange of the battery pack through the warning information and take suitable action.

The battery pack according to the present invention comprises the battery pack managing apparatus described above. That is, the battery pack may comprise a coupling detection unit110for detecting the coupling state of the bus bar and a controlling unit120for determining whether the coupling state of the bus bar has a defect on the basis of the coupling state detected by the coupling detection unit110. Particularly, the battery pack managing apparatus described above is preferably used as a battery pack for electric vehicles.

The vehicle according to the present invention comprises the battery pack managing apparatus described above. Particularly, the vehicle including the battery pack managing apparatus according to the present invention may be an electric vehicle.

Meanwhile, in embodiments ofFIGS. 1 to 5, for the convenience of explanation, two battery modules10are shown to be connected to each other. However, battery modules having three or more connections may also be applied in the present invention, which is apparent to those of ordinary skill in the art.

FIG. 6is a flow chart schematically illustrating a method for managing a battery pack according to one embodiment of the present invention. Each step ofFIG. 6may be carried out by each component of the battery pack managing apparatus described above.

Referring toFIG. 6, in order to manage the battery pack according to the present invention, the bus bar20, which is coupled with the battery modules10therebetween to electrically connect a plurality of the battery modules10with each other, is detected for its coupling state (S110). Here, step S110may be conducted by a pressure sensor111. The pressure sensor111may be a thin film-type. Also, step S110may be conducted by a voltage sensor112.

According to the detection results for the coupling state of the bus bar20to the battery modules10, the bus bar20is determined to have a defect or no defect in its coupling state (S120). At this time, in the case that step S110is conducted by a pressure sensor111, the bus bar20may be determined to have a defect in its coupling state in step S120when a pressure detected by the pressure sensor111is lower than a reference pressure value. Also, in the case that step S110is conducted by a voltage sensor112, the bus bar20may be determined to have a defect in its coupling state in step S120when the resistance of the bus bar20, which is calculated from a voltage detected by the voltage sensor112, is higher than a reference resistance value.

Preferably, if the bus bar20is determined to have a defect in its coupling state in step S120, the battery pack managing method of the present invention may further comprise the step of informing the coupling defect of the bus bar to a user (S130).

Also, if the bus bar20is determined to have a defect in its coupling state in step S120, the battery pack managing method may further comprise the step of interrupting the charge/discharge current of the battery modules10(S140).

Meanwhile, step S120may be conducted by a BMS.

Also, the steps of S110to S140are preferably applied in a battery pack for vehicles.

INDUSTRIAL APPLICABILITY

Meanwhile, the term ‘unit’ used herein just represents a logic unit, which may not be a component that can be physically separated, which is apparent to those of ordinary skill in the art.