Battery System

Abstract

The present invention provides a battery system capable of simply and accurately detecting a relay failure occurring in at least some of a plurality of battery packs connected in parallel. A battery system according to one aspect of the present invention comprises: a plurality of battery packs electrically connected in parallel with each other and each having a battery cell, a unit current path configured to allow a charge / discharge current to flow through the battery cell, and a unit relay provided in the unit current path, and further comprising at least one unit current sensor configured to measure the magnitude of the unit current flowing through the unit current path; an integrated current path connected together to the unit current path of each of the plurality of battery packs and configured to allow the charge / discharge current for the plurality of battery packs to flow in an integrated manner; an integrated current sensor provided in the integrated current path and configured to measure the magnitude of the integrated current flowing through the integrated current path; and a control unit configured to determine whether the unit relay has failed by comparing the unit current measured by the unit current sensor with the integrated current measured by the integrated current sensor.

Description

Technology Field

[0001] The present invention relates to a battery system, and more specifically, to a battery system configured to effectively determine whether a unit relay included in a battery pack is faulty when a plurality of battery packs are connected in parallel, and to an automobile and a power storage system including the same. Background Technology

[0002] Currently commercialized rechargeable batteries include nickel-cadmium, nickel-hydrogen, nickel-zinc, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages, such as the ability to charge and discharge freely with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0003] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. The lithium secondary battery comprises an electrode assembly in which a positive plate and a negative plate, each coated with the positive and negative active materials, are arranged with a separator in between, and an outer casing, namely a battery case, that seals and houses the electrode assembly together with an electrolyte.

[0004] Recently, secondary batteries are widely used for driving or energy storage not only in small devices such as portable electronic devices but also in medium-to-large devices such as automobiles and Energy Storage Systems (ESS). One or more secondary batteries may be provided in a battery pack and mounted on medium-to-large devices. In this case, to provide sufficient output or capacity to medium-to-large devices, each battery pack may be connected in parallel to form a single battery system.

[0005] In such battery systems, each battery pack may include charge / discharge current paths and relays (switches) that turn these paths on and off. Here, the relays included in each battery pack are often implemented using a mechanical method where contacts engage and disengage; however, failure situations may occur where these relays become stuck in a specific state and fail to operate properly. For example, a relay in a battery pack may become stuck in an open state, resulting in an open failure where it remains open instead of closing properly, even though it should.

[0006] In the event of such relay failure, the fault situation needs to be identified accurately and quickly. However, in situations where multiple battery packs are connected in parallel, measuring the battery system terminal voltage—such as the DC link voltage—cannot properly detect relay failures in some battery packs. This is because, due to the nature of the parallel connection, the final terminal voltage of the battery system remains nearly identical to that under normal conditions, even when relays in some battery packs fail.

[0007] If relay open failures in some battery packs are not properly diagnosed and the battery system continues to operate, battery packs without relay open failures may be overused beyond appropriate levels. Consequently, overall damage or degradation of the battery system may occur. Furthermore, in this case, a problem may arise where the battery system's capacity is not sufficiently secured. The problem to be solved

[0008] The present invention was devised to solve the above-mentioned problems and aims to provide a battery system capable of simply and accurately detecting a relay failure occurring in at least some of a plurality of battery packs connected in parallel, as well as an automobile and a power storage system including the same.

[0009] Other objects and advantages of the present invention may be understood from the following description and will become more clearly apparent from the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0010] A battery system according to the present invention for achieving the above-mentioned purpose comprises: a plurality of battery packs electrically connected in parallel with each other, each having a battery cell, a unit current path configured to allow a charge / discharge current to flow through the battery cell, and a unit relay provided in the unit current path, and further comprising at least one unit current sensor configured to measure the magnitude of the unit current flowing through the unit current path; an integrated current path connected together to the unit current path of each of the plurality of battery packs and configured to allow the charge / discharge current for the plurality of battery packs to flow in an integrated manner; an integrated current sensor provided in the integrated current path and configured to measure the magnitude of the integrated current flowing through the integrated current path; and a control unit configured to determine whether the unit relay is faulty by comparing the unit current measured by the unit current sensor with the integrated current measured by the integrated current sensor.

[0011] Here, the control unit may be configured to determine whether the unit relay is faulty by considering the number of parallel connections of the battery pack.

[0012] In addition, the control unit may be configured to determine whether at least one unit relay is faulty by comparing the integrated divided value, obtained by dividing the integrated current measured by the integrated current sensor by the number of parallel connections of the battery pack, with the unit current measured by at least one unit current sensor.

[0013] In addition, the control unit may be configured to determine that an open fault has occurred in at least one unit relay when the measured value of the unit current is greater than or equal to a certain level than the integrated divided value.

[0014] In addition, the plurality of battery packs each have a unit current sensor, and the control unit may be configured to compare the measured values ​​of the plurality of unit current sensors with each other when the measured value of the unit current is greater than or equal to a certain level than the integrated divided value.

[0015] In addition, the unit current sensor is configured to measure the unit current multiple times, and the control unit may be configured to determine that a fault has occurred in the unit relay based on the results measured multiple times by the unit current sensor.

[0016] In addition, the control unit may be configured to calculate an average value for a plurality of unit current measurements measured by the unit current sensor, and to determine that a fault has occurred in the unit relay by comparing the calculated average value with a reference value.

[0017] In addition, the control unit may be configured to determine that a fault has occurred in the corresponding unit relay if the calculated average value is lower than the reference value.

[0018] In addition, the automobile according to the present invention for achieving the above-mentioned purpose includes a battery system according to the present invention.

[0019] In addition, a power storage system according to the present invention for achieving the above-mentioned purpose includes a battery system according to the present invention. Effects of the invention

[0020] According to the present invention, when a plurality of battery packs are connected in parallel, a situation in which a failure occurs in a relay included inside at least some of the battery packs can be effectively identified.

[0021] In particular, according to one aspect of the present invention, whether an open fault has occurred in a relay of some battery packs can be diagnosed more accurately with only a simple configuration.

[0022] In addition, according to one aspect of the present invention, the failure status of a relay can be identified without individually determining whether each battery pack is in use.

[0023] Furthermore, according to one aspect of the present invention, a relay failure in a specific battery pack can be easily detected even if only the current value flowing through some battery packs is determined, without determining the current value flowing through each of all battery packs. Therefore, in this case, even in situations where some battery packs do not include a current sensor or where sensing information regarding the current sensor of some battery packs is not received, it can be determined whether a faulty relay is included within the battery system.

[0024] Therefore, according to these aspects of the present invention, relay failures in at least some battery packs can be identified quickly and accurately, thereby preventing other battery packs from being overused and damaged or degraded. Brief explanation of the drawing

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention described above; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a block diagram schematically illustrating the functional configuration of a battery system according to one embodiment of the present invention. FIG. 2 is a block diagram schematically showing the functional configuration of a battery pack included in a battery system according to one embodiment of the present invention. FIG. 3 is a circuit diagram schematically showing the connection configuration of a battery system according to one embodiment of the present invention. FIG. 4 is a graph showing the unit current measurement results measured multiple times by a unit current sensor provided in a battery pack in a battery system according to one embodiment of the present invention. FIGS. 5 and 6 are graphs showing the average value of unit current measurement results measured multiple times by unit current sensors provided in different battery packs in a battery system according to one embodiment of the present invention, compared with a reference value. Specific details for implementing the invention

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0027] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0029] FIG. 1 is a block diagram schematically illustrating the functional configuration of a battery system according to one embodiment of the present invention, and FIG. 2 is a block diagram schematically illustrating the functional configuration of a battery pack (100) included in a battery system according to one embodiment of the present invention. In addition, FIG. 3 is a circuit diagram schematically illustrating the connection configuration of a battery system according to one embodiment of the present invention.

[0030] Referring to FIGS. 1 to 3, the battery system according to the present invention may include a battery pack (100), an integrated current path (200), an integrated current sensor (300), and a control unit (400).

[0031] The above battery pack (100) may be included in a plurality in a battery system according to the present invention. For example, as shown in FIGS. 1 and 3, a battery system may include three battery packs (100), a first pack (101), a second pack (102), and a third pack (103). However, it is obvious to those skilled in the art that the number of battery packs (100) may be configured in various ways. In a battery system according to the present invention, such a plurality of battery packs (100) may be electrically connected in parallel with each other.

[0032] As illustrated in FIGS. 2 and 3, each battery pack (100) may be equipped with a battery cell (110), a unit current path (120), and a unit relay (130).

[0033] Here, the battery cell (110) may be configured to include one or more secondary batteries. In particular, to increase capacity and output, a plurality of secondary batteries may be included in the battery cell (110) in a form in which they are connected in series and / or parallel. The secondary batteries included in the battery cell (110) may be lithium secondary batteries, but the present invention is not necessarily limited to such types of secondary batteries.

[0034] The above unit current path (120) may be configured to allow charging and discharging current to flow for the battery cell (110). For example, the above unit current path (120) may be provided between the battery cell (110) and the pack terminal so that charging and discharging currents of the battery pack (100) flow between the battery cell (110) and the pack terminal.

[0035] The above unit relay (130) may be configured to be provided in a unit current path (120) to open or close the unit current path (120). In particular, the above unit relay (130) may be configured to allow or prevent current from flowing in the unit current path (120) through the contact and separation of contacts. For example, the above unit relay (130) may be a mechanical relay or an electronic relay. Since the configuration of such a unit relay (130) is widely known at the time of filing the present invention, a detailed description thereof is omitted, and various types of relays known at the time of filing the present invention may be employed as the unit relay (130) in the battery system of the present invention.

[0036] Additionally, at least one of the plurality of battery packs (100) included in the battery system may further be equipped with a unit current sensor (140). For example, as shown in FIG. 3, a unit current sensor (140) may be provided in all battery packs (100) included in the battery system. The unit current sensor (140) may be configured to measure the magnitude of the unit current flowing through the unit current path (120) of each battery pack (100). For example, in the configuration of FIG. 3, the unit current sensor (140) provided in the first pack (101) may be configured to measure the unit current flowing through the unit current path (120) of the first pack (101), i.e., the pack current. Various types of current sensors known at the time of filing the present invention may be employed as such a unit current sensor (140).

[0037] In addition to this, the battery pack (100) may be equipped with various other components. For example, the battery pack (100) may be further equipped with a measuring sensor for measuring the voltage or temperature of each battery pack (100), a fuse, and a Battery Management System (BMS) for controlling each unit relay (130) of the battery pack (100).

[0038] The above integrated current path (200) can be configured so that the charging and discharging currents for a plurality of battery packs (100) flow together. To this end, the above integrated current path (200) can be configured to be integrated and connected to each unit current path (120) of the plurality of battery packs (100).

[0039] For example, in the configuration of FIG. 3, each unit current path (120) of three battery packs (100) (first pack (101), second pack (102), and third pack (103)) can be connected to a single integrated terminal (210) and connected to an integrated current path (200). And, this integrated current path (200) can be connected to a charging and discharging system. More specifically, the integrated current path (200) can be connected to a charging device such as a charging terminal or power grid for charging the battery system, thereby providing a path through which charging power can be supplied to each battery pack (100). In addition, the integrated current path (200) can be connected to a load such as a motor or power grid, thereby providing a path through which the discharge power of each battery pack (100) can be discharged.

[0040] The integrated current sensor (300) may be provided on the integrated current path (200). The integrated current sensor (300) may be configured to measure the magnitude of the integrated current flowing in the integrated current path (200), i.e., the system current. As with the unit current sensor (140), various types of current sensors known at the time of filing the present invention may be employed for this integrated current sensor (300). Since such current sensors are widely known at the time of filing the present invention, a more detailed description of the configuration of the integrated current sensor (300) is omitted, and the present invention is not limited to a specific type of such integrated current sensor (300).

[0041] The above control unit (400) may be configured to compare the unit current measured by the unit current sensor (140) with the integrated current measured by the integrated current sensor (300).

[0042] For example, referring to the configuration of FIG. 3, the control unit (400) can be connected to the unit current sensor (140) of the first pack (101), the unit current sensor (140) of the second pack (102), and the unit current sensor (140) of the third pack (103), respectively (a1, a2, a3). Accordingly, the control unit (400) can receive the measured value of the unit current flowing in the unit current path (120) of each battery pack (100), that is, the measured value of each pack current, from these unit current sensors (140). Meanwhile, the control unit (400) may receive each unit current measured value directly from each unit current sensor (140) or may receive it through other components. For example, the control unit (400) may indirectly receive a unit current measurement value of each battery pack (100) through another control unit, such as a Battery Management System (BMS) provided in each battery pack (100). In addition, in the configuration of FIG. 3, the control unit (400) may be connected to an integrated current sensor (300) to receive a measurement value of the integrated current flowing in the integrated current path (200).

[0043] The control unit (400) can thus compare the measurement value of the integrated current received from the integrated current sensor (300) with the measurement value of the unit current received from the unit current sensor (140). Furthermore, the control unit (400) can be configured to determine whether there is a failure in the unit relay (130) included in at least one battery pack (100) through the result of comparing the integrated current and the unit current.

[0044] According to this configuration of the present invention, a relay failure inside the battery pack (100) included in the battery system can be simply and accurately identified solely by the current measurement results of the integrated current sensor (300) provided in the battery system and the unit current sensor (140) provided in the battery pack (100). Therefore, even if no significant change occurs in the voltage of the battery system—that is, in the voltage between the positive-side integrated current path (200) and the negative-side integrated current path (200) where a plurality of battery packs (100) are connected in parallel—a relay failure of the battery pack (100) can be easily diagnosed.

[0045] The above-described control unit (400) is known in the art for executing various control logics performed in the present invention and may optionally include or be expressed by terms such as a central processing unit (CPU), a processor, an application-specific integrated circuit (ASIC), a chipset, a logic circuit, a register, a communication modem, a data processing device, etc. Additionally, when the control logic is implemented in software, the above-described control unit (400) may be implemented as a set of program modules. In this case, the program modules may be stored in memory and executed by the control unit (400). The memory may be provided inside or outside the control unit (400) and may be connected to the control unit (400) by various well-known means.

[0046] Meanwhile, the integrated current path (200), the integrated current sensor (300), and the control unit (400) may be configured to be included in a single integrated device in which a plurality of battery packs (100) are connected, located outside the battery pack (100) as indicated by J in FIG. 3. For example, the integrated device indicated by J may be a junction box. That is, the integrated current path (200), the integrated current sensor (300), and the control unit (400) may be included in such a junction box.

[0047] Additionally, although not shown in the drawings, the battery system according to the present invention may further include an integrated relay (not shown) configured to be provided on the integrated current path (200) and to open and close the integrated current path (200). And, such an integrated relay may be turned on and off under the control of a control unit (400). For example, in an abnormal situation of the battery system, such as when a failure occurs in at least some unit relays (130), the control unit (400) may turn off the integrated relay so that current does not flow in the integrated current path or so that the battery system does not operate.

[0048] Additionally, the battery system according to the present invention may further include a warning unit. Accordingly, in an abnormal situation of the battery system, such as when a failure occurs in at least some unit relays (130), the warning unit may be configured to warn a user or manager of the situation using a monitor, lamp, speaker, etc.

[0049] Preferably, the control unit (400) may be configured to determine whether the unit relay (130) is faulty by considering the number of parallel connections of the battery pack (100).

[0050] For example, referring to the configuration illustrated in FIG. 3, if three battery packs (100) are connected in parallel to a battery system, the number of parallel connections of the battery packs (100) can be said to be three. In this case, the control unit (400) can use the number of parallel connections of the battery packs (100), which is three, when determining whether the unit relay (130) is faulty. Here, information regarding the number of parallel connections of the battery packs (100) may be stored in advance in a storage device such as a memory provided in the control unit (400), or may be provided from a separate device located outside the control unit (400). Alternatively, the control unit (400) may be configured to directly determine the number of parallel connections of the battery packs (100). For example, the control unit (400) may be configured to determine the number of parallel connections of the battery packs (100) by detecting the number of pack terminals connected to the integrated terminal (210).

[0051] More specifically, the control unit (400) can perform an operation in the form of dividing the measurement value of the integrated current received from the integrated current sensor (300) by the number of parallel connections of the battery pack (100). At this time, the value derived from such an operation can be called the integrated division value. For example, in a battery system as shown in FIG. 3, when the measurement value of the integrated current received from the integrated current sensor (300) is Iu, the control unit (400) can calculate the integrated division value as Iu / 3.

[0052] And, the control unit (400) may be configured to compare the unit current measurement value received from at least one unit current sensor (140) with the integrated division value. For example, in the configuration of FIG. 3, when the unit current measurement value is received as I1 from the unit current sensor (140) provided in the first pack (101), the control unit (400) may compare the first current measurement value I1 with the previously calculated integrated division value Iu / 3.

[0053] And, the control unit (400) may be configured to determine whether the unit relay (130) is faulty based on the result of comparing the unit current measurement value and the integrated divided value. For example, in the above embodiment, the control unit (400) may determine whether the unit relay (130) is faulty by comparing the magnitudes of the values ​​of I1 and Iu / 3 with each other. For instance, in FIG. 3, the unit relay (130) included in at least one battery pack (100) among the first pack (101), second pack (102), and third pack (103) may be faulty.

[0054] According to this configuration of the present invention, the control unit (400) can determine that a relay failure has occurred in at least some of the battery packs (100) among the plurality of battery packs (100) included in the battery system by only determining in advance the number of parallel connections of the battery packs (100) and comparing the measured values ​​of the plurality of current sensors with each other.

[0055] Additionally, among the plurality of battery packs (100) included in the battery system, some battery packs (100) may be intentionally not used depending on the situation. For example, if the requested current of the load connected to the battery system is small, some battery packs (100) may not be used. In such a situation, according to the above configuration of the present invention, even if the control unit (400) cannot determine whether all battery packs (100) are in use, it can determine whether a failure has occurred in the relay of at least some battery packs (100). Furthermore, according to the above configuration of the present invention, even in a situation where no current sensor is included in all battery packs (100), or where a sensing value is not received from the current sensor of all battery packs (100), it can determine whether a failure has occurred in the relay of at least some battery packs (100).

[0056] More preferably, the control unit (400) can compare the unit current measurement value with the integrated division value, and if the unit current measurement value is greater than the integrated division value by a certain level or more, determine that an open fault has occurred in at least one unit relay (130). Here, an open fault refers to a fault in which the contact of the unit relay (130) remains in a disconnected state and fails to properly close even if there is a close control signal. In other words, an open fault refers to a fault situation in which the unit relay (130) is stuck in an open state. And, a certain level refers to a current difference within an error range that can occur even when the battery system is in a normal state without any failure in some unit relays (130). For example, the certain level may refer to a level of approximately 0.5 A as an error range.

[0057] As a more specific example, as shown in the configuration of FIG. 3, there are three battery packs (100) of a first pack (101), a second pack (102), and a third pack (103), and when the integrated current measured by the integrated current sensor (300) is 30A, the integrated divided value can be calculated as 30A / 3, i.e., 10A. At this time, when the measurement value by the unit current sensor (140) provided in the first pack (101), i.e., the unit current measured value flowing in the first pack (101), is 15A, it can be seen as deviating from a certain level when compared to 10A. Accordingly, the control unit (400) can determine that an open fault has occurred in at least one of the plurality of unit relays (130).

[0058] In particular, the control unit (400) can determine that if the unit current measurement value is greater than the integrated division value, the unit relay (130) provided in a battery pack (100) other than the target battery pack (100) of the unit current compared with the integrated division value is an open fault.

[0059] For example, in the above embodiment, if the unit current measurement value flowing in the first pack (101) is 15A and is detected to be greater than the integrated divided value of 10A, the control unit (400) may determine that an open fault has occurred in the unit relay (130) provided in the second pack (102) or the unit relay (130) provided in the third pack (103), rather than in the first pack (101).

[0060] In a configuration where multiple battery packs (100) are connected in parallel, if the unit relay (130) of some battery packs (100) is open fault, unit current cannot flow through the corresponding battery pack (100). On the other hand, since the voltage across all terminals of the parallel-connected battery packs (100) is the same, even if the unit relay (130) of some battery packs (100) is open fault, the magnitude of the current flowing through the integrated current path (200) does not change significantly. However, in other battery packs (100) where the unit relay (130) operates normally, more current can flow than in normal conditions. For example, in the above embodiment, if the unit relay (130) of the third pack (103) is faulty, more current flows through the first pack (101) and the second pack (102) than in normal conditions.

[0061] Accordingly, according to the above embodiment of the present invention, the fact that a problem has occurred in a unit relay (130) within the battery system can be recognized by sensing only the unit current flowing in some battery packs (100). That is, even without checking the current sensing information of each of all battery packs (100), the fact that a problem has occurred in some unit relays (130) can be easily identified.

[0062] Additionally, a plurality of battery packs (100) included in the battery system according to the present invention may each be equipped with a unit current sensor (140). For example, as shown in FIG. 3, the first pack (101), the second pack (102), and the third pack (103) may each be equipped with a unit current sensor (140).

[0063] At this time, the control unit (400) may be configured to compare the measurement values ​​of a plurality of unit current sensors (140) with each other when the measurement value of the unit current is greater than or equal to a certain level than the integrated divided value.

[0064] For example, as in the preceding embodiment, if the integrated split value is 10A and the unit current measurement value of the first pack (101) is detected to be 15A or higher than a certain level, the control unit (400) can compare the unit current measurement value of the first pack (101) with the unit current measurement value of the second pack (102) and / or the third pack (103).

[0065] Here, the control unit (400) can compare whether at least two unit current measurements are identical. And, through such comparison of identicalness, the accuracy of the unit current measurements can be verified. For example, if the unit current measurement of the first pack (101) is 15A, it can be determined whether the unit current measurement of the second pack (102) and / or the third pack (103) is 15A. If the unit current measurement of the second pack (102) is 15A, since this is identical to the unit current measurement of the first pack (101), the control unit (400) can determine that the unit current measurement of the first pack (101) was measured accurately. And, the control unit (400) can determine that an open fault has occurred in the unit relay (130) of a battery pack (100) other than the first pack (101) and the second pack (102), such as the third pack (103).

[0066] According to this configuration of the present invention, since it is possible to verify whether the current measurement value of the unit current sensor (140) is accurate, the open fault of the unit relay (130) can be determined more accurately.

[0067] Additionally, the control unit (400) can determine whether there is a unit current sensor (140) with a current measurement value of 0 when the unit current measurement value of some battery packs (100) is greater than the integrated divided value. And, the control unit (400) can determine that the unit relay (130) is open fault for the battery pack (100) in which the magnitude of the unit current is determined to be 0.

[0068] For example, in the embodiment of FIG. 3, the control unit (400) can determine whether there is a current sensor with a measurement value of 0 among the unit current sensors (140) of the second pack (102) or the third pack (103) when the measurement value of the unit current sensor (140) of the first pack (101) is 15A, which is greater than the integrated divided value of 10A. If the unit current of the third pack (103) is sensed as 0, the control unit (400) can determine that the unit relay (130) of the third pack (103) is faulty. At this time, the control unit (400) can perform related controls, such as warning the user to replace the third pack (103) or cutting off the current of the battery system.

[0069] According to this configuration of the present invention, since the magnitude of another unit current is determined to be zero only when the unit current of some battery packs (100) is greater than normal, unnecessary verification operations can be prevented.

[0070] Additionally, the control unit (400) may determine that an open fault has occurred in the corresponding unit relay (130) if the measured value of the unit current is smaller than the integrated divided value by a certain level or more. Here, the corresponding unit relay (130) may be the unit relay (130) of the battery pack (100) where the unit current, which is the target compared with the integrated divided value, is measured.

[0071] For example, in a situation where the integrated split value is 10A, if the unit current measurement value of the first pack (101) is 0, the control unit (400) can determine that an open fault has occurred in the unit relay (130) of the first pack (101).

[0072] At this time, the control unit (400) can further compare the unit current measurement values ​​of other battery packs (100). In particular, the control unit (400) can determine whether the unit current measurement value of other battery packs (100) is measured to be larger than the integrated divided value. For example, if the unit current measurement value of the first pack (101) is 0, it can determine whether the unit current measurement value of the second pack (102) and / or the third pack (103) is detected to be larger than 10A by a certain level. And, if the unit current measurement values ​​of the second pack (102) and the third pack (103) are larger than 10A by a certain level, such as 15A each, the control unit (400) can determine that an open fault has occurred in the unit relay (130) of the first pack (101). On the other hand, if the unit current measurement value of the second pack (102) and the third pack (103) is not measured to be greater than the integrated divided value of 10A, it may be greater than the unit current sensor (140) of the first pack (101), so the control unit (400) can perform a re-verification operation, such as receiving the measurement value again from the unit current sensor (140) of the first pack (101).

[0073] According to this configuration of the present invention, since the magnitude of another unit current is determined to be above a certain level only when the unit current of some battery packs (100) is smaller than normal, unnecessary verification operations can be prevented. In addition, according to the above embodiment, even if the unit current of some battery packs (100) is temporarily measured to be low, the failure of the unit relay (140) is not immediately determined as a final failure, but rather the failure of the unit relay (140) can be finally determined by verifying through the measurement results of other battery packs (100). Therefore, the failure of the unit relay (140) can be determined more accurately.

[0074] Additionally, the unit current sensor (140) may be configured to measure the unit current multiple times. In particular, the unit current sensor (140) may be configured to repeatedly measure the unit current periodically or non-periodically over a predetermined period.

[0075] And, the control unit (400) can determine that an open fault has occurred in the unit relay (130) based on the results measured multiple times by the unit current sensor (140). That is, the control unit (400) can be configured to use multiple unit current measurements rather than a single unit current measurement value when determining whether the unit relay (130) has an open fault. This will be explained in more detail with reference to FIG. 4.

[0076] FIG. 4 is a graph showing the unit current measurement results measured multiple times by a unit current sensor (140) provided in a battery pack (100) in a battery system according to one embodiment of the present invention.

[0077] Referring to FIG. 4, unit current values ​​measured 12 times by a unit current sensor (140) are displayed as 12 points (P1 to P12). That is, each point represents a unit current measurement result measured at a specific point in time. Then, the control unit (400) can determine that a failure has occurred in the unit relay (130) of the corresponding battery pack (100) or the unit relay (130) of another battery pack (100) by considering these multiple measurement results.

[0078] For example, the measurement result of FIG. 4 can be assumed to be the result measured by a unit current sensor (140) provided in the first pack (101) in a battery system including three battery packs (100) as in the embodiment of FIG. 3. In addition, in a situation where all unit relays (130) provided in the three battery packs (100) are operating normally, the value measured by all unit current sensors (140) can be assumed to be 10A. In this situation, the result measured by the unit current sensor (140) provided in the first pack (101) can be said to indicate a normal state as 10A at points P1 and P2. However, at points P3, P4, and P5, it shows a measurement value higher than the normal state as 15A. Then, at points P6 and P7, the unit current measurement result again shows a normal state as 10A, but at points P8, P9, and P10, it shows a high value as 15A.

[0079] In this situation, the control unit (400) can check whether the unit relay (130) has an open failure by considering the situation in which normal and abnormal states are repeated. In particular, as shown in FIG. 4, if the unit current measurement result by the unit current sensor (140) shows a normal and abnormal situation, it can be interpreted that at least some unit relays (130) are unintentionally repeating open and closed states. For example, even though a close signal is transmitted to the unit relay (130), the contact does not remain closed, and a failure may occur in a half-open state where closing and closing are repeated. As a more specific example, it can be seen that a specific unit relay is normally closed at points P1, P2, P6, P7, P11, and P12, but a specific unit relay is abnormally open at points P3, P4, P5, P8, P9, and P10.

[0080] However, according to the above embodiment, the failure situation of such unit relay (130), particularly the semi-open failure situation, can be identified more accurately. For example, in FIG. 4, if the presence or absence of a unit relay (130) of the battery system is determined based only on the measurement results of point P1 or point P2, it can be determined that there is no abnormality in the unit relay (130). However, in the above embodiment, since the failure situation of the unit relay (130) is identified by utilizing the results (P1~P12) measured several times over a predetermined period, a more accurate failure of the unit relay (130) can be identified. Furthermore, according to the above embodiment, even the semi-open failure situation of the unit relay (130) can be effectively identified.

[0081] In particular, the control unit (400) may be configured to calculate an average value for a plurality of unit current measurements measured by the unit current sensor (140). Furthermore, the control unit (400) may be configured to determine that an open fault has occurred in the unit relay (130) by comparing the average value calculated in this way with a reference value. This will be explained in more detail with reference to FIGS. 5 and 6.

[0082] FIGS. 5 and 6 are graphs showing the average value of a unit current measurement result measured multiple times by a unit current sensor (140) provided in different battery packs (100) in a battery system according to one embodiment of the present invention, compared with a reference value.

[0083] First, the straight line m1 in FIG. 5 can be said to represent the average value of a plurality of unit current measurements taken for one of the plurality of battery packs (100) included in the battery system, such as the first pack (101) in FIG. 3. For example, m1 in FIG. 5 can be said to represent the average value of the 12 current measurement results in FIG. 4. In this case, the average value can be said to be a representative value for the plurality of unit current measurements. This average value may be an arithmetic mean value, but the present invention is not necessarily limited to such an embodiment, and the control unit (400) can calculate the average value in various ways to obtain an approximation for the plurality of measurements. In addition, the average value may be configured in the form of a straight line as shown in FIG. 5, but may be configured in various forms such as a curve or a bent straight line.

[0084] When the average value is calculated in this way, the control unit (400) can compare the calculated average value with the reference value. In FIG. 5, the reference value is indicated by the dotted line r0. This reference value can be said to be a value that can be measured by each unit relay (130) in a situation where all unit relays (130) of the entire battery pack (100) included in the battery system are normal. The reference value can be stored in advance in the memory of the control unit (400), etc. The control unit (400) can compare whether the calculated average value (m1) is greater than or less than this reference value (r0) by a certain level.

[0085] And, through this comparison, the control unit (400) can determine whether a failure has occurred in the unit relay (130) of the battery pack (100) or in the unit relay (130) of another battery pack (100). For example, as shown in FIG. 5, if the average unit current value (m1) of the first pack (101) is greater than a reference value (r0) by a certain level, it can be determined that a failure, particularly an open failure or a semi-open failure, has occurred in the unit relay (130) of a battery pack (100) other than the battery pack (100), such as the second pack (102) or the third pack (103).

[0086] Furthermore, the control unit (400) can determine whether a fully open fault or a half-open fault has occurred in a predetermined unit relay (130) by considering the difference between the average unit current value and the reference value.

[0087] For example, in the configuration of FIG. 5, as indicated by g1, the control unit (400) can determine whether the difference between the unit current average value (m1) and the reference value (r0) is greater or smaller than a predetermined gap reference value. Here, the gap reference value may be a value set to distinguish between a state where a full open fault has occurred and a state where a half-open fault has occurred. And, the control unit (400) can determine that a full open fault has occurred in the unit relay (130) of another battery pack (100) when the unit current average value (m1) is greater than the reference value (r0) and the difference (g1) between them is greater than the gap reference value. On the other hand, when the unit current average value (m1) is greater than the reference value (r0) and the difference (g1) between them is smaller than the gap reference value, it can determine that a half-open fault has occurred in the unit relay (130) of another battery pack (100).

[0088] For example, in the configuration of FIG. 5, if the gap reference value is 4A, and g1 is 5A, since this is greater than the gap reference value, the control unit (400) can determine that a full open failure of the unit relay (130) has occurred in the second pack (102) or the third pack. On the other hand, if g1 is 2A, since this is less than the gap reference value, the control unit (400) can determine that a half open failure of the unit relay (130) has occurred in the second pack (102) or the third pack (103).

[0089] According to this configuration of the present invention, the normal state, fully open fault state, and half-open fault state of the unit relay (130) can be more easily distinguished through the difference between the unit current average value and the reference value.

[0090] Additionally, the control unit (400) can determine that a failure has occurred in the corresponding unit relay (130), that is, in the unit relay (130) of the battery pack (100) where the average value of the unit current was calculated, if the calculated average value is lower than the reference value.

[0091] For example, referring to FIG. 6, the straight line m2 can be said to represent the average value of a plurality of unit current measurements taken for the second pack (102) of FIG. 3. And, the dotted line r0 can be said to be a reference value, as in FIG. 5 above.

[0092] In the case of Fig. 6, the line m2, which is the average unit current value of the second pack (102), can be said to be lower than the reference value (r0) by a certain level. Therefore, the control unit (400) can determine that a failure has occurred in the unit relay (130) of the battery pack (100), that is, the second pack (102).

[0093] In particular, the control unit (400) can determine that a semi-open fault has occurred in the second pack (102) if the average unit current value (m2) of the second pack (102) is lower than the reference value (r0) but greater than 0.

[0094] Alternatively, the control unit (400) can determine whether a complete open fault has occurred in the corresponding unit relay (130) or a half open fault has occurred by considering the difference between the unit current average value (m2) and the reference value (r0), as in the embodiment of FIG. 5.

[0095] For example, in the configuration of FIG. 6, as indicated by g2, the control unit (400) can determine whether the difference between the average unit current value (m2) and the reference value (r0) is greater or smaller than a predetermined gap reference value. Here, the gap reference value may have a different value from the gap reference value of FIG. 5. For example, the gap reference value in the configuration of FIG. 6 may be set to be larger than the gap reference value in the configuration of FIG. 5. And, in a situation where the average unit current value (m2) is smaller than the reference value (r0), if the gap (g2) between them is larger than the gap reference value, the control unit (400) can determine that a complete open fault has occurred in the unit relay (130) of the battery pack (100), that is, the unit relay (130) of the second pack (102). On the other hand, in a situation where the average unit current value (m2) is smaller than the reference value (r0), if the difference (g2) between them is smaller than the gap reference value, it can be determined that a semi-open fault has occurred in the unit relay (130) of the battery pack (100).

[0096] Meanwhile, in the configuration of FIGS. 5 and FIGS. 6 above, the reference value is depicted as a single line, but such a reference value may be configured in the form of a certain range. That is, the reference value may be set to a certain range considering measurement errors, etc.

[0097] Additionally, the control unit (400) can determine whether the unit relay (130) is in a fully open state or a partially open state based on the measurement pattern of the unit current measurement results measured multiple times. For example, the control unit (400) can determine that the unit relay (130) of another battery pack (100) is in a partially open state if the unit current measurement result of a specific battery pack (100) repeatedly changes in a region higher than the reference value. On the other hand, the control unit (400) can determine that the unit relay (130) of the battery pack (100) is in a partially open state if the unit current measurement result of a specific battery pack (100) repeatedly changes in a region lower than the reference value.

[0098] The battery system according to the present invention may be installed in an automobile, particularly an electric vehicle. That is, the automobile according to the present invention may include the battery system according to the present invention. Here, a part of the battery system, such as a control unit (400), may be implemented as a component provided on the automobile side, such as an ECU (Electronic Control Unit). In addition, the automobile according to the present invention may include a vehicle body or electronic equipment, etc., that are typically provided in an automobile, in addition to the battery system. For example, the automobile according to the present invention may include an inverter, a motor, and one or more ECUs, etc., in addition to the battery system according to the present invention. However, the present invention does not specifically limit other components of the automobile, etc., other than the battery system.

[0099] In addition, the battery system according to the present invention may be included in an energy storage system (ESS). That is, the energy storage system according to the present invention may include the battery system according to the present invention. In particular, in the case of an energy storage system, a very large number of battery packs (100) are typically connected in parallel to secure a large capacity. In the case of the battery system according to the present invention, if a failure occurs in the unit relay (130) of some battery packs (100) among the battery packs (100) connected in parallel, it is possible to identify the issue simply, more quickly, and accurately, thereby enabling effective operation when adopted in an energy storage system.

[0101] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0102] 100: Battery pack 101: Pack 1, 102: Pack 2, 103: Pack 3 110: Battery cell, 120: Unit current path, 130: Unit relay, 140: Unit current sensor 200: Integrated current path 210: Integrated terminal 300: Integrated current sensor 400: Control unit

Claims

Claim 1 A battery system characterized by comprising: a plurality of battery packs each electrically connected in parallel with one another, each having a battery cell, a unit current path configured to allow a charge / discharge current to flow through the battery cell, and a unit relay provided in the unit current path, and further having at least one unit current sensor configured to measure the magnitude of the unit current flowing through the unit current path; an integrated current path connected together to the unit current path of each of the plurality of battery packs to allow the charge / discharge current for the plurality of battery packs to flow in an integrated manner; an integrated current sensor provided in the integrated current path and configured to measure the magnitude of the integrated current flowing through the integrated current path; and a control unit configured to compare the unit current measured by the unit current sensor with the integrated current measured by the integrated current sensor, and to determine whether the unit relay is faulty based on the result of the comparison between the unit current and the integrated current. Claim 2 A battery system according to claim 1, wherein the control unit is configured to determine whether the unit relay is faulty by considering the number of parallel connections of the battery pack. Claim 3 A battery system according to paragraph 2, wherein the control unit is configured to determine whether at least one unit relay is faulty by comparing the integrated divided value obtained by the integrated current sensor, divided by the number of parallel connections of the battery pack, with the unit current measured by at least one unit current sensor. Claim 4 A battery system according to paragraph 3, wherein the control unit is configured to determine that an open fault has occurred in at least one unit relay when the measured value of the unit current is greater than or equal to a certain level than the integrated divided value. Claim 5 A battery system according to claim 4, wherein each of the plurality of battery packs is equipped with a unit current sensor, and the control unit is configured to compare the measured values ​​of the plurality of unit current sensors with each other when the measured value of the unit current is greater than or equal to a certain level than the integrated divided value. Claim 6 A battery system according to claim 1, wherein the unit current sensor is configured to measure the unit current multiple times, and the control unit is configured to determine that a fault has occurred in the unit relay based on the results measured multiple times by the unit current sensor. Claim 7 A battery system according to claim 6, wherein the control unit is configured to calculate an average value for a plurality of unit current measurements measured by the unit current sensor, and to determine that a fault has occurred in the unit relay by comparing the calculated average value with a reference value. Claim 8 A battery system according to claim 7, wherein the control unit is configured to determine that a fault has occurred in the corresponding unit relay when the calculated average value is lower than the reference value. Claim 9 An automobile comprising a battery system according to any one of paragraphs 1 through 8. Claim 10 A power storage system comprising a battery system according to any one of paragraphs 1 through 8.

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