Fusion diagnosis method and battery system using the same

Abstract

The battery system may include a plurality of battery packs, a plurality of positive relays connected between a positive electrode and a positive electrode link of a corresponding battery pack for each of the plurality of packs, a plurality of negative relays connected between a negative electrode and a negative electrode link of a corresponding battery pack for each of the plurality of packs, and a plurality of pack BMS (Battery Management Systems) connected to the plurality of battery packs. Each of the plurality of pack BMSs may diagnose whether the corresponding positive relay is fused based on a first battery pack current flowing through the corresponding battery pack when the plurality of negative relays are closed, when a difference between both ends of a corresponding positive relay is smaller than a first critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0002133, dated January 6, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present disclosure relates to a fusion diagnosis method and a battery system using the same. [Background technology]

[0003] Generally, when diagnosing whether a positive relay connected to the positive electrode of a battery pack and a negative relay connected to the negative electrode of the battery pack are stuck closed, the voltage of the positive electrode of the battery pack is compared with the voltage of a link connected to the positive electrode relay, or the voltage of the negative electrode of the battery pack is compared with the voltage of a link connected to the negative electrode relay. However, when multiple battery packs are connected in parallel, it is difficult to diagnose whether each of the positive and negative relays of the multiple battery packs is stuck closed using the above method.

[0004] Furthermore, even if a fusion diagnosis occurs, it is difficult to determine which of the multiple battery packs has a positive electrode relay and a negative electrode relay that have fused, or how many battery packs are connected to the positive electrode relay and the negative electrode relay that have fused. Summary of the Invention [Problem to be solved by the invention]

[0005] To provide a method for accurately diagnosing whether each of a plurality of relays is fused when a plurality of battery packs are connected in parallel. [Means for solving the problem]

[0006] A battery system according to one aspect of the present invention may include a plurality of battery packs, a plurality of positive relays connected between a positive electrode and a positive link of a corresponding battery pack in each of the plurality of packs, a plurality of negative relays connected between a negative electrode and a negative link of a corresponding battery pack in each of the plurality of packs, and a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs. Each of the plurality of pack BMSs may diagnose whether the corresponding positive relay is fused based on a first battery pack current flowing through the corresponding battery pack when the plurality of negative relays are closed, when a difference in voltage across the corresponding positive relay is less than a first critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays.

[0007] Each of the plurality of pack BMSs may determine that the corresponding positive relay is fused when the first battery pack current is greater than a first critical current.

[0008] Under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, when a difference in voltage across at least one of the plurality of positive electrode relays is smaller than the first critical voltage, each of the plurality of pack BMSs may measure a battery pack current flowing through each of the plurality of battery packs while sequentially closing each of the plurality of negative electrode relays one by one.

[0009] When the voltage of the negative link is lower than a second critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays, each of the plurality of pack BMSs can diagnose whether the corresponding negative relay is fused based on a second battery pack current flowing through each of the plurality of battery packs when each of the plurality of positive relays is closed sequentially one by one.

[0010] Each of the plurality of pack BMSs may determine that the corresponding negative relay is fused when the second battery pack current is greater than a second critical current.

[0011] Each of the plurality of pack BMSs may determine, under an open control condition for the plurality of positive electrode relays and the plurality of negative electrode relays, that a positive electrode relay and a negative electrode relay connected to a battery pack through which a battery pack current greater than a third critical current flows among battery pack currents flowing through each of the plurality of battery packs is fused.

[0012] According to another aspect of the present invention, a battery system may include a plurality of battery packs, a plurality of positive relays connected between a positive electrode and a positive link of a corresponding battery pack in each of the plurality of packs, a plurality of negative relays connected between a negative electrode and a negative link of a corresponding battery pack in each of the plurality of packs, and a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs. Each of the plurality of pack BMSs may diagnose at least one positive relay and at least one negative relay through which at least one battery pack current flows as fused when at least one of a plurality of battery pack currents flowing through the plurality of battery packs is greater than a third critical current under an open control condition of the plurality of positive relays and the plurality of negative relays.

[0013] Each of the plurality of pack BMSs can diagnose whether the corresponding positive electrode relay is fused based on a first battery pack current flowing through the corresponding battery pack when the corresponding negative electrode relay is closed, when all of the plurality of battery pack currents are equal to or less than a third critical current and a difference in voltage across the corresponding positive electrode relay is smaller than a first critical voltage under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays.

[0014] Each of the plurality of pack BMSs can diagnose whether a corresponding negative relay is fused based on a second battery pack current flowing through the corresponding battery pack when the corresponding positive relay is closed, when all of the plurality of battery pack currents are equal to or less than a third critical current and the voltage of the negative link is lower than a second critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays.

[0015] According to another aspect of the invention, a method for diagnosing fusion of a plurality of positive electrode relays connected to positive electrodes of a plurality of battery packs and a plurality of negative electrode relays connected to negative electrodes of the plurality of battery packs may include the steps of: each of a plurality of pack BMSs connected to the plurality of battery packs comparing a difference in voltage across each of the plurality of positive electrode relays with a first critical voltage under an open control condition for the plurality of positive electrode relays and the plurality of negative electrode relays; sequentially closing the plurality of negative electrode relays one by one when at least one of the differences in the voltage across each of the plurality of positive electrode relays is smaller than the first critical voltage; comparing a battery pack current flowing through each of the plurality of battery packs with a first critical current; and determining that at least one positive electrode relay through which at least one current flows is fused when at least one of the plurality of battery pack currents of the plurality of battery packs is larger than the first critical current.

[0016] According to another aspect of the invention, a method for diagnosing fusion of a plurality of positive electrode relays connected to positive electrodes of a plurality of battery packs and a plurality of negative electrode relays connected to negative electrodes of the plurality of battery packs may include the steps of: in each of a plurality of pack BMSs connected to the plurality of battery packs, under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, comparing a voltage of a negative electrode link connected to a corresponding negative electrode relay with a critical voltage; sequentially closing the plurality of positive electrode relays one by one when the voltage of the negative electrode link is lower than the second critical voltage; comparing a battery pack current flowing in each of the plurality of battery packs with a second critical current; and determining that at least one negative electrode relay through which at least one battery pack current flows is fused when at least one of the plurality of battery pack currents of the plurality of battery packs is higher than the second critical current. [Effects of the Invention]

[0017] The present invention provides a fusion diagnosis method capable of accurately diagnosing whether each of a plurality of relays is fused when a plurality of battery packs are connected in parallel, and a battery system using the same. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram illustrating a battery system according to one embodiment. [Figure 2] FIG. 2 is a circuit diagram illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment. [Figure 3] FIG. 3 is a flowchart illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment. [Figure 4] FIG. 4 is a circuit diagram illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment. [Figure 5]FIG. 5 is a circuit diagram illustrating a method for determining whether a plurality of negative electrode relays are fused according to one embodiment. [Figure 6] FIG. 6 is a flowchart illustrating a method for determining whether a plurality of negative relays are fused according to one embodiment. [Figure 7] FIG. 7 is a circuit diagram illustrating a method for determining whether a plurality of negative electrode relays are fused according to one embodiment. [Figure 8] FIG. 8 is a circuit diagram for explaining a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment. [Figure 9] FIG. 9 is a flowchart illustrating a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment. [Figure 10] FIG. 10 is a flow chart showing a variation on the embodiment shown in FIG. [Figure 11] FIG. 11 is a flow chart showing another variation of the embodiment shown in FIG. [Figure 12] FIG. 12 is a circuit diagram illustrating a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by identical or similar drawing numbers, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" for components used in the following description are added or used interchangeably solely for the convenience of writing the specification, and do not have any distinct meaning or function. Furthermore, in describing the embodiments disclosed herein, if it is determined that a detailed description of related publicly known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are intended to facilitate understanding of the embodiments disclosed herein, and should not be construed as limiting the technical concepts disclosed herein, and should be understood to include all modifications, equivalents, or alternatives within the concept and technical scope of the present invention.

[0020] Terms including ordinal numbers such as "first," "second," etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0021] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0022] In this application, the use of terms such as "comprise" or "have" is intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof stated in the specification, but should be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0023] FIG. 1 is a diagram illustrating a battery system according to one embodiment.

[0024] The battery system 1 includes a plurality of battery packs 10-30, a main control integrated circuit (IC) 40, and a junction device 50. Although FIG. 1 shows three battery packs, the invention is not limited to this, and the battery system 1 may include four or more battery packs. Furthermore, while FIG. 1 shows the plurality of battery packs 10-30 connected in parallel, two or more battery packs may be connected in series, and the series-connected battery packs may be connected in parallel.

[0025] The external power device 2 may be a load supplied with power from the battery system 1, or a charger for charging the battery system 1. For example, the external power device 2 may include at least one of an inverter, a DC-DC converter, a motor, an electronic control circuit, an OBC (On Board Charger), and a fast charger of a vehicle including the battery system 1.

[0026] The battery packs 10 to 30 are connected in parallel with each other, and both ends of the battery packs 10 to 30 are connected to the junction device 50 via lines 151 and 152. The junction device 50 may include a first main relay 51 connected between the line 151 and the external power device 2 and a second main relay 52 connected between the line 152 and the external power device 2. The first and second main relays 51 and 52 control the connection between the battery packs 10 to 30 and the external power device 2, and the main control IC 40 may generate a relay control signal MRS for controlling the operation of the first and second main relays 51 and 52 and transmit the signal to the junction device 50. The junction device 50 may control the opening and closing of the first and second main relays 51 and 52 according to the relay control signal MRS. Although FIG. 1 illustrates the junction device 2 as including a pair of main relays, the number of pairs of main relays may be determined depending on the number of external power devices 2.

[0027] Each of the battery packs 10-30 includes a plurality of battery cells 11-14, 21-24, 31-34, a plurality of pack battery management systems 100, 200, 300, two relays 101, 102, 201, 202, 301, 302, and a current sensor 103, 203, 303. The pack battery management system is hereinafter referred to as a pack BMS (Battery Management System). While FIG. 1 illustrates each of the battery packs 10-30 including four battery cells 11-14, 21-24, 31-34, this is merely an example, and the invention is not limited thereto. Furthermore, each of the battery packs 10-30 includes two relays, but this is merely an example, and the number of relays may be at least one.

[0028] Each of the plurality of pack BMSs 100, 200, 300 is connected to a plurality of battery cells 11-14, 21-24, 31-34 and measures the cell voltages of the plurality of battery cells 11-14, 21-24, 31-34. Each of the plurality of pack BMSs 100, 200, 300 can obtain the voltage (hereinafter referred to as battery pack voltage), current (hereinafter referred to as battery pack current), and temperature (hereinafter referred to as battery pack temperature) of each of the battery packs 10, 20, 30. Each of the plurality of pack BMSs 100, 200, 300 can control the charging and discharging of the battery packs 10-30 based on the cell voltages, battery pack currents, etc. of the plurality of battery cells 11-14, 21-24, 31-34 and can control and perform cell balancing operations for the plurality of battery cells 11-14, 21-24, 31-34.

[0029] The multiple pack BMSs 100, 200, 300 can control the opening and closing of each of the multiple relays 101, 102, 201, 202, 301, 302 to control the charging and discharging of the multiple battery packs 10 to 30. Each of the multiple pack BMSs 100, 200, 300 can generate two drive signals RLS1 / RLS2, RLS3 / RLS4, RLS5 / RLS6 that control the opening and closing of two relays 101 / 102, 201 / 202, 301 / 302 and supply them to the two relays 101 / 102, 201 / 202, 301 / 302.

[0030] The main control IC 40 can receive information regarding the cell voltages of the plurality of battery cells 11-15, 21-25, and 31-35, the battery pack voltages, battery pack currents, and battery pack temperatures of the plurality of battery packs 10, 20, and 30 from the plurality of pack BMSs 100, 200, and 300. The main control IC 40 can supply power control signals to the plurality of pack BMSs 100, 200, and 300 to supply power to the outside, or can supply charge control signals to the plurality of pack BMSs 100, 200, and 300 to charge the plurality of battery packs 10, 20, and 30. In addition, the main control IC 40 performs control necessary for the operation of the battery system 1, and can activate and control a protective operation when an abnormal state of the battery system 1 is detected.

[0031] In one embodiment, it is described that the plurality of pack BMSs 100, 200, 300 determine whether the plurality of relays 101 / 102, 201 / 202, 301 / 302 are fused. However, the invention is not limited to this, and the main control IC 40 can determine whether the plurality of relays 101 / 102, 201 / 202, 301 / 302 are fused based on cell information received from the plurality of pack BMSs 100, 200, 300. Hereinafter, of the plurality of relays 101 / 102, 201 / 202, 301 / 302, a relay connected to the positive electrode of the battery pack is referred to as a positive relay, and a relay connected to the negative electrode of the battery pack is referred to as a negative relay.

[0032] Each of the plurality of pack BMSs 100, 200, 300 is connected to both ends of each of the plurality of positive relays 101, 201, 301, and can calculate a voltage difference between both ends. For example, one end of each of the plurality of positive relays 101, 201, 301 is connected to the positive electrode of each of the plurality of battery packs 10, 20, 30, and the other end of each of the plurality of positive relays 101, 201, 301 is connected to a wiring 151. The voltage of one end of each of the plurality of positive relays 101, 201, 301 may be the same as the positive electrode voltage of the corresponding battery pack, and the voltage of the other end of each of the plurality of positive relays 101, 201, 301 may be the same as the voltage of a positive link (hereinafter, positive link voltage). The positive link may be the wiring 151 connecting the positive electrodes of the plurality of battery packs 100, 200, 300 to the external power device 2.

[0033] Each of the multiple pack BMSs 100, 200, 300 is connected to the positive electrode of each of the multiple battery packs 100, 200, 300, and can measure the positive electrode voltage of each of the multiple battery packs 100, 200, 300. The multiple pack BMSs 100, 200, 300 are connected to wiring 151 and can measure the positive electrode voltage. The multiple pack BMSs 100, 200, 300 include a switch (not shown) connected to wiring 151, and can be turned on to measure the positive electrode link voltage.

[0034] One end of each of the negative relays 102, 202, 302 is connected to the negative electrode of each of the battery packs 10, 20, 30, and the other end of each of the negative relays 102, 202, 302 is connected to a wiring 152. The voltage of the other end of each of the negative relays 102, 202, 302 may be the same as the voltage of the negative link (hereinafter, negative link voltage). The negative link may be the wiring 152 connecting the negative electrodes of the battery packs 100, 200, 300 to the external power device 2. Each of the pack BMSs 100, 200, 300 is connected to the wiring 152 and can measure the negative link voltage. The pack BMSs 100, 200, 300 include a switch (not shown) connected to the wiring 152 and can be turned on to measure the negative link voltage.

[0035] Each of the plurality of current sensors 103, 203, 303 can measure the battery pack current and transmit a signal indicative of the measured current to each of the plurality of pack BMSs 100, 200, 300.

[0036] Hereinafter, a method for determining whether two relays connected to each of the plurality of battery packs 10, 20, 30 in each of the plurality of pack BMSs 100, 200, 300 are fused will be described with reference to FIGS. 2 to 12.

[0037] FIG. 2 is a circuit diagram illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment.

[0038] FIG. 3 is a flowchart illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment.

[0039] For ease of explanation, Fig. 2 shows a plurality of battery packs 100, 200, 300, a plurality of positive relays 101, 201, 301 connected to each battery pack, and a plurality of negative relays 102, 202, 302. Also, Fig. 2 shows the positive relay 101 in a fused state. In Fig. 2, the closed states of the plurality of negative relays 102, 202, 302 are shown by dotted lines.

[0040] First, each of the plurality of pack BMSs 100, 200, 300 can wake up for fusion diagnosis (S0). A monitoring operation for diagnosing the state of the battery system 1 can be performed by the plurality of pack BMSs 100, 200, 300. For example, the plurality of pack BMSs 100, 200, 300 can wake up at each monitoring period to determine whether each of the plurality of positive relays 101, 201, 301 is fused.

[0041] The multiple pack BMSs 100, 200, 300 can control the opening of the multiple positive pole relays 101, 201, 301 and the multiple negative pole relays 102, 202, 302 (S1).

[0042] The multiple pack BMSs 100, 200, 300 can calculate the difference in voltage across the multiple positive relays 101, 201, 301 (S2). For example, each of the multiple pack BMSs 100 can measure the voltages VA1, VA2, VA3 and the positive link voltage VL1 at one end of each of the multiple positive relays 101, 201, 301, and calculate the absolute value of the voltage value obtained by subtracting the positive link voltage VL1 from the voltages VA1, VA2, VA3 at one end as the difference in voltage across the multiple positive relays 101, 201, 301.

[0043] The multiple pack BMSs 100, 200, 300 compare the multiple end-to-end voltage differences |VA1-VL1|, |VA2-VL1|, |VA3-VL1| with a first critical voltage VTH1 (S3). If the comparison result indicates that the multiple end-to-end voltage differences |VA1-VL1|, |VA2-VL1|, |VA3-VL1| are equal to or greater than the first critical voltage, the multiple pack BMSs 100, 200, 300 end the fusion diagnosis for the multiple positive pole relays 101, 201, 301 (S7).

[0044] When one of the positive relays 101, 201, and 301 is fused, the positive link voltage VL1 may be similar to the positive voltage of the battery pack supplied through the fused positive relay. Because the battery packs 10, 20, and 30 operate in a parallel connection state, the positive voltages of the battery packs 10, 20, and 30 may be substantially similar to each other under the open control conditions of the positive and negative relays. Therefore, due to the fused positive relay, the voltage differences |VA1-VL1|, |VA2-VL1|, and |VA3-VL1| across all of the positive relays 101, 201, and 301 may be less than the first critical voltage VTH1. Conversely, when none of the positive relays 101, 201, and 301 are fused, the voltages |VA1-VL1|, |VA2-VL1|, and |VA3-VL1| across all of the positive relays may be greater than the first critical voltage VTH1.

[0045] If the comparison result indicates that at least one of the multiple end-to-end voltage differences |VA1-VL1|, |VA2-VL1|, and |VA3-VL1| is smaller than the first critical voltage VTH1, each of the multiple pack BMSs 100, 200, and 300 can sequentially close each of the multiple negative relays 102, 202, and 302 one by one (S4). The order in which each of the multiple pack BMSs 100, 200, and 300 closes its corresponding negative relay can be controlled by the main controller 40. The main controller 40 can close the junction device 50 while measuring the multiple battery pack currents IB1, IB2, and IB3. As indicated by the dotted lines in FIG. 2, each of the multiple negative relays 102, 202, and 302 is sequentially closed one by one.

[0046] Each of the plurality of pack BMSs 100, 200, 300 compares each of the plurality of battery pack currents IB1, IB2, IB3 measured by each of the plurality of current sensors 103, 203, 303 with a first critical current ITH1 (S5).

[0047] If the battery pack current IB1 among the plurality of battery pack currents IB1, IB2, and IB3 is greater than the first critical current ITH1, the pack BMS 100 can determine that the positive relay 101 is fused (S6).

[0048] If the battery pack currents IB2 and IB3 are equal to or less than the first critical current ITH1, the pack BMSs 200 and 300 end the fusion diagnosis, and the pack BMS 100 also ends the fusion diagnosis after determining that the positive relay 101 is fused (S7).

[0049] The multiple pack BMSs 100, 200, 300 can transmit fusion diagnosis results to the main control device 40. If there is a fused positive relay, the main control device 40 can control the junction device 50 to an open state. In addition, the main control device 40 can perform an operation to notify that the positive relay 101 is fused. For example, the main control device 40 can transmit information indicating that the positive relay 101 is fused to a vehicle equipped with the battery system 1 via CAN communication.

[0050] FIG. 4 is a circuit diagram illustrating a method for determining whether a plurality of positive relays are fused according to one embodiment.

[0051] In Fig. 4, the two positive relays 101 and 301 are shown in a fused state, unlike Fig. 2. Below, the contents that overlap with those explained above will be omitted.

[0052] As shown in FIG. 4, since the two positive relays 101 and 301 are in a fused state, the voltage differences |VA1-VL1|, |VA2-VL1|, and |VA3-VL1| between the positive relays 101, 201, and 301 may be smaller than the first critical voltage VTH1.

[0053] Each of the multiple pack BMSs 100, 200, 300 can sequentially close each of the multiple negative relays 102, 202, 302 one by one, and compare each of the multiple battery pack currents IB1, IB2, IB3 flowing through each of the multiple battery packs 10, 20, 30 with a first critical current ITH1.

[0054] As a result of the comparison, if the battery pack currents IB1, IB3 among the plurality of battery pack currents IB1, IB2, IB3 are greater than the first critical current ITH1, the pack BMS 100, 300 can determine that the positive relays 101, 103 are fused.

[0055] The first critical current ITH1 can be set taking into consideration the case where two or more battery positive relays are fused. For example, if two or more battery positive relays are fused, the number of current paths supplied to the vehicle depends on the number of fused positive relays. Therefore, compared to the case where one positive relay is fused, if two or more positive relays are fused, the battery pack current flowing through the fused positive relays may be reduced. The first critical current ITH1 should be set taking this into consideration.

[0056] FIG. 5 is a circuit diagram illustrating a method for determining whether a plurality of negative electrode relays are fused according to one embodiment.

[0057] FIG. 6 is a flowchart illustrating a method for determining whether a plurality of negative relays are fused according to one embodiment.

[0058] For ease of explanation, Fig. 5 shows a plurality of battery packs 100, 200, 300, a plurality of positive relays 101, 201, 301 connected to each battery pack, and a plurality of negative relays 102, 202, 302. Also, Fig. 5 shows the negative relay 102 in a fused state. In Fig. 5, the closed states of the plurality of positive relays 101, 201, 301 are indicated by dotted lines.

[0059] First, each of the plurality of pack BMSs 100, 200, 300 can wake up for fusion diagnosis (S10). A monitoring operation for diagnosing the state of the battery system 1 can be performed by the plurality of pack BMSs 100, 200, 300. For example, the plurality of pack BMSs 100, 200, 300 can wake up at each monitoring period to determine whether each of the plurality of negative electrode relays 102, 202, 302 is fused.

[0060] The multiple pack BMSs 100, 200, 300 can control the opening of the multiple positive pole relays 101, 201, 301 and the multiple negative pole relays 102, 202, 302 (S11).

[0061] The multiple pack BMSs 100, 200, 300 can measure the negative link voltage VL2 (S12).

[0062] The pack BMSs 100, 200, 300 compare the negative link voltage VL2 with the second critical voltage VHT2 (S13). If the comparison result indicates that the negative link voltage VL2 is equal to or greater than the second critical voltage VHT2, the pack BMSs 100, 200, 300 terminate the fusion diagnosis for the negative relays 102, 202, 302 (S17).

[0063] If the comparison result indicates that the negative link voltage VL2 is lower than the second critical voltage VTH2, each of the plurality of pack BMSs 100, 200, 300 sequentially closes each of the plurality of positive relays 101, 201, 301 one by one (S14). The order in which each of the plurality of pack BMSs 100, 200, 300 closes its corresponding positive relay may be controlled by the main controller 40. The main controller 40 may close the junction device 50 while measuring the plurality of battery pack currents IB1, IB2, IB3. As indicated by the dotted lines in FIG. 5, each of the plurality of positive relays 101, 201, 301 is sequentially closed.

[0064] Each of the plurality of pack BMSs 100, 200, 300 compares each of the plurality of battery pack currents IB1, IB2, IB3 measured by each of the plurality of current sensors 103, 203, 303 with a second critical current ITH2 (S15).

[0065] If the battery pack current IB1 among the plurality of battery pack currents IB1, IB2, and IB3 is greater than the second critical current ITH2, the pack BMS 100 may determine that the negative relay 102 is fused (S16).

[0066] If the battery pack currents IB2 and IB3 are equal to or less than the second critical current ITH2, the pack BMSs 200 and 300 end the fusion diagnosis, and the pack BMS 100 also ends the fusion diagnosis after determining that the negative electrode relay 102 is fused (S17).

[0067] The multiple pack BMSs 100, 200, 300 can transmit fusion diagnosis results to the main control device 40. If there is a fused negative relay, the main control device 40 can control the junction device 50 to an open state. In addition, the main control device 40 can perform an operation to notify that the negative relay 102 is fused. For example, information indicating that the negative relay 102 is fused can be transmitted to a vehicle equipped with the battery system 1 via CAN communication.

[0068] FIG. 7 is a circuit diagram illustrating a method for determining whether a plurality of negative electrode relays are fused according to one embodiment.

[0069] In Fig. 7, the two negative electrode relays 102, 302 are shown in a fused state, unlike Fig. 5. Below, the contents that overlap with those explained above will be omitted.

[0070] As shown in FIG. 7, since the two negative relays 102, 302 are in a fused state, the negative link voltage VL2 is less than the second critical voltage VTH2.

[0071] Each of the plurality of pack BMSs 100, 200, 300 can sequentially close each of the plurality of positive relays 101, 201, 301 one by one, and compare each of the plurality of battery pack currents IB1, IB2, IB3 with the second critical current ITH2.

[0072] Among the plurality of battery pack currents IB1, IB2, IB3, if the battery pack current IB1, IB3 is greater than the fourth critical current ITH4, the pack BMS 100, 300 may determine that the negative relay 102, 302 is fused.

[0073] The second critical current ITH2 can be set taking into account the case where two or more battery negative relays are fused. For example, if two or more battery negative relays are fused, the number of current paths supplied to the vehicle depends on the number of fused negative relays. Therefore, compared to the case where one negative relay is fused, if two or more negative relays are fused, the battery pack current flowing through the fused negative relays may be reduced. The second critical current ITH2 should be set taking this into consideration.

[0074] Although the embodiment described above may perform fusion diagnosis on a plurality of positive relays or a plurality of negative relays, the invention is not limited thereto, and an embodiment may perform fusion diagnosis on a positive relay and a negative relay connected to each of a plurality of battery packs.

[0075] FIG. 8 is a circuit diagram for explaining a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment.

[0076] FIG. 9 is a flowchart illustrating a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment.

[0077] For ease of explanation, Fig. 8 shows a plurality of battery packs 100, 200, 300, a plurality of positive relays 101, 201, 301 connected to each battery pack, and a plurality of negative relays 102, 202, 302. Also, Fig. 8 shows the positive relay 101 and the negative relay 102 in a fused state.

[0078] First, each of the plurality of pack BMSs 100, 200, 300 can wake up for fusion diagnosis (S20). A monitoring operation for diagnosing the state of the battery system 1 can be performed by the plurality of pack BMSs 100, 200, 300. For example, the plurality of pack BMSs 100, 200, 300 can wake up at each monitoring period to determine whether the plurality of positive electrode relays 101, 201, 301 and the plurality of negative electrode relays 102, 202, 302 are fused.

[0079] The multiple pack BMSs 100, 200, 300 can control the multiple positive pole relays 101, 201, 301 and the multiple negative pole relays 102, 202, 302 to open (S21).

[0080] Each of the plurality of pack BMSs 100, 200, 300 compares each of the battery pack currents IB1, IB2, IB3 flowing through each of the plurality of battery packs 10, 20, 30 with a third critical current ITH3 under an open circuit control condition (S22). The plurality of battery pack currents IB1, IB2, IB3 may be measured by each of the plurality of current sensors 103, 203, 303.

[0081] If the comparison result in step S22 indicates that at least one (e.g., IB1) of the plurality of battery pack currents IB1, IB2, and IB3 is greater than the third critical current ITH3, the pack BMS 10 determines that the positive electrode relay 101 and the negative electrode relay 102 are fused (S23). At this time, the battery pack currents IB2 and IB3 may be less than the third critical current ITH3. After step S23, each of the plurality of pack BMSs 100, 200, and 300 may end the fusion diagnosis (S24).

[0082] As a result of the comparison in step S22, when all of the plurality of battery pack currents IB1, IB2, IB3 are equal to or less than the third critical current ITH3, each of the plurality of pack BMSs 100, 200, 300 can perform a positive relay diagnosis through steps S0 to S7 or a negative relay diagnosis through steps S10 to S17.

[0083] FIG. 10 is a flow chart showing a variation on the embodiment shown in FIG.

[0084] FIG. 11 is a flow chart showing another variation of the embodiment shown in FIG.

[0085] In each of FIGS. 10 and 11, when all of the currents of the plurality of battery packs are equal to or less than the third critical current in step S22, the subsequent operation is different from the embodiment shown in FIG.

[0086] As shown in FIG. 10, each of the plurality of pack BMSs 100, 200, 300 may perform the positive relay diagnosis S0 to S7 and then the negative relay diagnosis S10 to S17.

[0087] Alternatively, as shown in FIG. 11, each of the plurality of pack BMSs 100, 200, 300 may perform the negative relay diagnosis S10 to S17 and then the positive relay diagnosis S0 to S7.

[0088] FIG. 12 is a circuit diagram illustrating a method for determining whether a plurality of positive relays and a plurality of negative relays are fused according to one embodiment.

[0089] As shown in Figure 12, when the positive electrode relay 101 and the negative electrode relay 302 are fused, the multiple pack BMSs 100, 200, 300 can first perform steps S20 to S23 using the method shown in Figure 9. In the circuit shown in Figure 10, all of the multiple battery pack currents IB1, IB2, IB3 are less than or equal to the third critical current ITH3, so the diagnosis ends.

[0090] Next, each of the plurality of pack BMSs 100, 200, 300 can perform positive relay diagnosis through steps S0 to S7 and negative relay diagnosis through steps S10 to S17. Conversely, each of the plurality of pack BMSs 100, 200, 300 can perform negative relay diagnosis through steps S10 to S17 and positive relay diagnosis through steps S0 to S7.

[0091] This allows pack BMS 100 to determine if positive relay 101 is fused and pack BMS 200 to determine if negative relay 302 is fused.

[0092] According to one embodiment, in a battery system in which a plurality of battery packs are connected in parallel, it is possible to accurately diagnose a fused relay among a plurality of relays.

[0093] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these examples, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. Multiple battery packs and a plurality of positive electrode relays connected between the positive electrodes of the corresponding battery packs and the positive electrode links, respectively; a plurality of negative electrode relays connected between the negative electrodes of the corresponding battery packs and the negative electrode links, respectively; a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs; Each of the plurality of pack BMSs includes: and when a difference in voltage across a corresponding positive relay is smaller than a first critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays, the battery system diagnoses whether the corresponding positive relay is fused based on a first battery pack current flowing through the corresponding battery pack when the corresponding negative relay is closed.

2. Each of the plurality of pack BMSs includes:

10. The battery system of claim 1, wherein the corresponding positive relay is determined to be fused when the first battery pack current is greater than a first critical current.

3. When a difference between both ends of a voltage of at least one of the plurality of positive electrode relays is smaller than the first critical voltage under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, Each of the plurality of pack BMSs includes: measuring a battery pack current flowing through each of the plurality of battery packs while sequentially closing each of the plurality of negative electrode relays one by one; The battery system of claim 1 .

4. A plurality of battery packs; a plurality of positive electrode relays connected between the positive electrodes of the corresponding battery packs and the positive electrode links, respectively; a plurality of negative electrode relays connected between the negative electrodes of the corresponding battery packs and the negative electrode links, respectively; a plurality of pack BMSs (Battery Management Systems) connected to the plurality of battery packs; Each of the plurality of pack BMSs includes: and when the voltage of the negative link is lower than a second critical voltage under an open control condition of the plurality of positive relays and the plurality of negative relays, the battery system diagnoses whether a corresponding negative relay is fused based on a second battery pack current flowing through each of the plurality of battery packs when each of the plurality of positive relays is closed one by one in sequence.

5. Each of the plurality of pack BMSs includes:

5. The battery system of claim 4, wherein the corresponding negative relay is determined to be fused when the second battery pack current is greater than a second critical current.

6. Each of the plurality of pack BMSs includes:

6. The battery system according to claim 1, wherein, under the open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, a positive electrode relay and a negative electrode relay connected to a battery pack through which a battery pack current greater than a third critical current flows among battery pack currents flowing through each of the plurality of battery packs is determined to be fused.

7. Multiple battery packs and a plurality of positive electrode relays connected between the positive electrodes of the corresponding battery packs and the positive electrode links, respectively; a plurality of negative electrode relays connected between the negative electrodes of the corresponding battery packs and the negative electrode links, respectively; a plurality of pack BMSs coupled to the plurality of battery packs; Each of the plurality of pack BMSs includes: When at least one of a plurality of battery pack currents flowing through the plurality of battery packs is greater than a third critical current under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, the at least one positive electrode relay and the at least one negative electrode relay through which the at least one battery pack current flows are diagnosed as fused; When all of the currents of the battery packs are equal to or less than a third critical current under an open control condition of the positive electrode relays and the negative electrode relays, When a difference in voltage across a corresponding positive relay is smaller than a first critical voltage, the battery system diagnoses whether the corresponding positive relay is fused based on a first battery pack current flowing through the corresponding battery pack when the corresponding negative relay is closed.

8. A plurality of battery packs; a plurality of positive electrode relays connected between the positive electrodes of the corresponding battery packs and the positive electrode links, respectively; a plurality of negative electrode relays connected between the negative electrodes of the corresponding battery packs and the negative electrode links, respectively; a plurality of pack BMSs coupled to the plurality of battery packs; Each of the plurality of pack BMSs includes: When at least one of a plurality of battery pack currents flowing through the plurality of battery packs is greater than a third critical current under an open control condition of the plurality of positive electrode relays and the plurality of negative electrode relays, the at least one positive electrode relay and the at least one negative electrode relay through which the at least one battery pack current flows are diagnosed as fused; When all of the currents of the battery packs are equal to or less than a third critical current under an open control condition of the positive electrode relays and the negative electrode relays, When the voltage of the negative electrode link is lower than a second critical voltage, the battery system diagnoses whether the corresponding negative electrode relay is fused based on a second battery pack current that flows through the corresponding battery pack when the corresponding positive electrode relay is closed.

9. A fusion diagnosis method for diagnosing fusion of a plurality of positive electrode relays connected to positive electrodes of a plurality of battery packs and a plurality of negative electrode relays connected to negative electrodes of the plurality of battery packs, comprising: Each of the plurality of pack BMSs connected to the plurality of battery packs includes: comparing a difference between voltages across each of the plurality of positive pole relays with a first critical voltage under an open control condition of the plurality of positive pole relays and the plurality of negative pole relays; Sequentially closing the plurality of negative relays one by one when at least one of the plurality of voltage differences is smaller than the first critical voltage; comparing a battery pack current flowing through each of the plurality of battery packs with a first critical current; and determining that at least one positive relay through which at least one of a plurality of battery pack currents of the plurality of battery packs flows is fused when the at least one positive relay current is greater than the first critical current.

10. A fusion diagnosis method for diagnosing fusion of a plurality of positive electrode relays connected to positive electrodes of a plurality of battery packs and a plurality of negative electrode relays connected to negative electrodes of the plurality of battery packs, comprising: Each of the plurality of pack BMSs connected to the plurality of battery packs includes: Under an open control condition of the plurality of positive pole relays and the plurality of negative pole relays, comparing a voltage of a negative pole link connected to a corresponding negative pole relay with a second critical voltage; If the voltage of the negative link is less than the second critical voltage, sequentially closing the plurality of positive relays one by one; comparing a battery pack current flowing through each of the plurality of battery packs with a second critical current; and determining that at least one negative relay through which at least one of a plurality of battery pack currents of the plurality of battery packs flows is fused when the at least one negative relay through which at least one of the plurality of battery pack currents flows is greater than the second critical current.

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