External short circuit diagnosis method and battery system using the same

Abstract

The battery system may include a battery pack including a plurality of battery cells, a first main relay having one end connected to a positive electrode of the battery pack, a second main relay having one end connected to a negative electrode of the battery pack, a first link wiring connected to the other end of the first main relay, a second link wiring connected to the other end of the second main relay, and a battery management system that closes the first main relay, measures a positive electrode voltage of the battery pack and a negative link voltage of the second link wiring, and determines an external short circuit to occur when a voltage difference between the positive electrode voltage of the battery pack and the negative link voltage is smaller than a predetermined reference voltage.

Description

[Technical field]

[0001] [Cross-reference to related applications (etc.)] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0002134 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 an external short circuit diagnosis method and a battery system to which the same is applied. [Background technology]

[0003] Currently, a method for diagnosing an external short circuit for a high voltage battery pack uses a current flowing through a pre-charging path during pre-charging of the high voltage battery pack. For example, a battery management system of the high voltage battery measures a current flowing through a link wire between the high voltage battery pack and an external device during pre-charging of the high voltage battery. When the measured current is equal to or greater than a threshold, the battery management system protects the high voltage battery from an external short circuit by cutting off the connection between the battery pack and the external device.

[0004] However, when the above method is used, a large amount of current flows through the link wiring during the pre-charging period before the connection is cut off, which may cause damage to the relay and resistor connected between the high-voltage battery pack and the external device, as well as to the high-voltage battery pack. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an external short circuit diagnosis method capable of diagnosing an external short circuit without damaging elements constituting a battery system, and a battery system using the same. [Means for solving the problem]

[0006] According to one aspect of the invention, a battery system may include a battery pack including a plurality of battery cells, a first main relay having one end connected to a positive electrode of the battery pack, a second main relay having one end connected to a negative electrode of the battery pack, a first link wiring connected to the other end of the first main relay, a second link wiring connected to the other end of the second main relay, and a battery management system that closes the first main relay, measures a positive electrode voltage of the battery pack and a negative link voltage of the second link wiring, and determines an external short circuit to have occurred when a voltage difference between the positive electrode voltage of the battery pack and the negative link voltage is smaller than a predetermined reference voltage.

[0007] The battery management system may determine an external short circuit when a voltage obtained by subtracting the negative link voltage from a positive electrode voltage of the battery pack is smaller than the reference voltage.

[0008] The battery management system may generate the reference voltage by multiplying a positive electrode voltage of the battery pack by a predetermined ratio.

[0009] The battery management system may close the first main relay and open the second main relay for a predetermined diagnostic period to determine an external short circuit.

[0010] The battery system may further include a pre-charge relay connected in parallel to the first main relay, and the battery management system may close the first main relay and open the pre-charge relay for a predetermined diagnostic period for determining an external short circuit.

[0011] The battery system may include a first main relay having one end connected to a positive electrode of a battery pack including a plurality of battery cells, a second main relay having one end connected to a negative electrode of the battery pack, and a battery management system. According to another feature of the invention, a method for diagnosing an external short circuit in a battery system performed by the battery management system may include the steps of closing the first main relay for a diagnosis period, measuring a positive electrode voltage of the battery pack and a negative link voltage of the second link wiring, comparing a voltage difference between the positive electrode voltage and the negative link voltage of the battery pack with a predetermined reference voltage, and determining an external short circuit when the voltage difference is smaller than the reference voltage.

[0012] The step of comparing the voltage difference with a predetermined reference voltage may include the step of comparing whether a voltage obtained by subtracting the negative link voltage from a positive electrode voltage of the battery pack is smaller than the reference voltage.

[0013] The method for diagnosing an external short circuit in a battery system may further include generating the reference voltage by multiplying a positive electrode voltage of the battery pack by a predetermined ratio.

[0014] The method for diagnosing an external short circuit in a battery system may further include opening the second main relay during the diagnosis period.

[0015] The method for diagnosing an external short circuit in a battery system may further include opening a pre-charge relay connected in parallel to the first main relay during the diagnosis period. Effect of the Invention

[0016] The present invention provides an external short circuit diagnosis method capable of diagnosing an external short circuit without damaging elements constituting a battery system, and a battery system to which the same is applied. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a battery system according to an embodiment. [Diagram 2] 1 is a diagram illustrating a case where an external short circuit occurs in a battery system according to an embodiment. [Diagram 3] 1 is a flowchart illustrating an external short circuit diagnosis method according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings. The same or similar components are given the same or similar reference numerals, and the duplicated description thereof will be omitted. The suffixes "module" and / or "part" for components used in the following description are given or mixed for the sake of ease of writing the specification, and do not have any meaning or role that is different from each other. In addition, when describing the embodiments disclosed in the present specification, if it is determined that a detailed description of related known technology may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are provided to facilitate understanding of the embodiments disclosed in the present specification, and the technical ideas disclosed in the present specification are not limited by the accompanying drawings, and it should be understood that the accompanying drawings include all modifications, equivalents, or alternatives included in the ideas and technical scope of the present invention.

[0019] 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.

[0020] When a component is referred to as being "coupled" or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. In contrast, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0021] In this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof set forth in the specification, but are to be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0022] FIG. 1 is a diagram showing a battery system according to one embodiment.

[0023] The battery system 1 may include a battery pack 10, a Battery Management System (BMS) 20, a first main relay 31, a second main relay 32, a precharge relay 33, a precharge resistor 34, a current sensor 50, and a link capacitor 60.

[0024] The external power device 2 may be a load that receives 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 high-speed charger of a vehicle including the battery system 1.

[0025] 1, the battery pack 10 includes a plurality of battery cells 10_1-10_n connected in series, where n may be a natural number equal to or greater than 2. Although one battery pack 10 is shown in FIG 1, the battery system 1 may include a plurality of battery packs connected in series, parallel, or series-parallel.

[0026] The current sensor 50 senses a current flowing through the battery pack 10 (hereinafter, battery pack current), and the current sensor 50 may transmit a signal indicative of the sensed current to the BMS 20.

[0027] The link capacitor 60 is connected between the two output terminals P+ and P− of the battery system 1 .

[0028] The BMS 20 may manage the operation of the battery pack 10. For example, the BMS 20 may be connected to a plurality of battery cells 10_1-10_n, measure cell voltages of the plurality of battery cells 10_1-10_n, receive information such as a battery pack current and a temperature of the battery pack 10, control charging and discharging of the battery pack 10 based on the plurality of cell voltages, the battery pack current, the temperature, etc. of the plurality of battery cells 10_1-10_n, and control a cell balancing operation for the plurality of battery cells 10_1-10_n.

[0029] The first main relay 31, the second main relay 32, and the pre-charge relay 33 form a current path through which a charging current or a discharging current flows for the battery pack 10. The pre-charge relay 33 is connected in parallel to the first main relay 31 together with a pre-charge resistor 34.

[0030] One end of the first main relay 31 is connected to the link wiring 41, and the other end of the first main relay 31 is connected to the link wiring 43. One end of the second main relay 32 is connected to the link wiring 42, and the other end of the second main relay 32 is connected to the link wiring 44. One end of the pre-charge relay 33 is connected to the link wiring 43, and the other end of the pre-charge relay 33 is connected to one end of the pre-charge resistor 34, and the other end of the pre-charge resistor 34 is connected to the link wiring 41.

[0031] The link wiring 41 extends between the positive electrode of the battery pack 10 and one end of the first main relay 31, the link wiring 42 extends between the negative electrode of the battery pack 10 and one end of the second main relay 32, the link wiring 43 extends between the other end of the first main relay 31 and the first input terminal IN1 of the external power device 2, and the link wiring 44 extends between the other end of the second main relay 32 and the second input terminal IN2 of the external power device 2.

[0032] The BMS 20 can generate relay control signals RCS1 to RCS3 that control the opening and closing of the first and second main relays 31, 32 and the pre-charge relay 33, and supply them to the first and second main relays 31, 32 and the pre-charge relay 33. The first main relay 31 is closed by the on level of the relay control signal RCS1, and is opened by the off level of the relay control signal RCS1. The second main relay 32 is closed by the on level of the relay control signal RCS2, and is opened by the off level of the relay control signal RCS2. The pre-charge relay 33 is closed by the on level of the relay control signal RCS3, and is opened by the off level of the relay control signal RCS3.

[0033] When the battery pack 10 and the external power device 2 are connected for charging and discharging, the BMS 20 may control the second main relay 32 and the pre-charge relay 33 to be closed, and may control the first main relay 31 to be closed after a predetermined first period has elapsed. The BMS 20 may control the pre-charge relay 33 to be opened after a predetermined second period has elapsed from the time the first main relay 31 is closed. In order to control the above operations, the BMS 20 may generate on-level relay control signals RCS2 and RCS3, generate an on-level relay control signal RCS1 after the first period has elapsed, and generate an off-level relay control signal RCS3 after the second period has elapsed.

[0034] The BMS 20 may close only the first main relay 31 for a predetermined diagnostic period before charging / discharging in order to diagnose an external short circuit of the battery system 1. During the diagnostic period, only the relay control signal RCS1 may be at an on level, and the relay control signals RCS2 and RCS3 may be at an off level.

[0035] The BMS 20 may measure the voltage of the link wiring 44 during the diagnostic period, and determine that an external short circuit has occurred if the voltage difference between the measured voltage of the link wiring 44 (hereinafter, the negative link voltage) VL− and the positive electrode voltage VP+ of the battery pack 10 is equal to or less than a predetermined reference voltage.

[0036] FIG. 2 is a circuit diagram illustrating a battery system during a diagnostic period for an external short circuit, according to one embodiment.

[0037] 2, an external short circuit may result in an electrical connection, shown by the dotted line, between link wire 43 and link wire 44. During the diagnostic period, first main relay 31 is in a closed state.

[0038] FIG. 3 is a flowchart showing an external short-circuiting method according to an embodiment.

[0039] First, the BMS 20 closes the first main relay 31 (S1). That is, the BMS 20 generates an on-level relay control signal RCS1 and supplies it to the first main relay 31. The BMS 20 opens the second main relay 32 and the pre-charge relay 33 during a diagnostic period for performing an external short circuit.

[0040] The BMS 20 measures (S2) the positive electrode voltage VP+ and the negative link voltage VL- of the battery pack 10. The BMS 20 may measure the positive electrode voltage of the battery cell 10_1 as the positive electrode voltage VP+ of the battery pack 10, and measure the voltage of the link wiring 44 as the negative link voltage VL-.

[0041] The BMS 20 calculates (S3) a voltage difference VD between the positive electrode voltage VP+ and the negative link voltage VL- of the battery pack 10. For example, the BMS 20 may calculate the voltage difference by subtracting the negative link voltage VL- from the positive electrode voltage VP+.

[0042] The BMS 20 compares the voltage difference VD with a reference voltage VR (S4). For example, the BMS 20 can compare whether the voltage difference VD is smaller than the reference voltage VR, and the BMS 20 can generate the reference voltage VR by multiplying the measured positive electrode voltage VP+ of the battery pack 10 by a predetermined ratio (e.g., 50%). The ratio of 50% is just an example, and the present invention is not limited thereto.

[0043] If the comparison result in step S4 indicates that the voltage difference VD is smaller than the reference voltage VR, the BMS 20 determines that an external short circuit has occurred (S5). When an external short circuit occurs, the positive electrode of the battery pack 10 is electrically connected to the link wiring 44 via the first main relay 31 and the short circuit 45. Then, the negative link voltage VL- may become a level close to the positive electrode voltage VP+. Therefore, the voltage difference VD between the positive electrode voltage VP+ and the negative link voltage VL- becomes a very small voltage due to the external short circuit. The reference voltage VR may be set to a level for detecting the voltage difference VD when an external short circuit occurs.

[0044] If the voltage difference is equal to or greater than the reference voltage as a result of the comparison in step S4, the BMS 20 determines that the state is normal and no external short circuit occurs, and ends the diagnosis (S6). In the normal state, the negative link voltage VL- may be 0V.

[0045] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these embodiments, and various modifications and improvements made by those having ordinary skill in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. a battery pack including a plurality of battery cells; a first main relay including one end connected to a positive electrode of the battery pack; a second main relay including one end connected to the negative electrode of the battery pack; a first link wiring connected to the other end of the first main relay; a second link wiring connected to the other end of the second main relay; a battery management system for closing the first main relay, measuring a positive electrode voltage of the battery pack and a negative link voltage of the second link wiring, and determining an external short circuit when a voltage difference between the positive electrode voltage of the battery pack and the negative link voltage is smaller than a predetermined reference voltage. Battery system.

2. The battery management system includes:

2. The battery system according to claim 1, wherein an external short circuit is determined when a voltage obtained by subtracting the negative link voltage from the positive electrode voltage of the battery pack is smaller than the reference voltage.

3. The battery management system includes: The battery system according to claim 2 , wherein the reference voltage is generated by multiplying a positive electrode voltage of the battery pack by a predetermined ratio.

4. The battery management system includes:

4. The battery system according to claim 1, wherein the first main relay is closed and the second main relay is opened for a predetermined diagnostic period for determining an external short circuit.

5. a pre-charge relay connected in parallel to the first main relay, The battery management system includes:

4. The battery system according to claim 1, wherein the first main relay is closed and the pre-charge relay is opened for a predetermined diagnostic period for determining an external short circuit.

6. A method for diagnosing an external short circuit in a battery system including a first main relay having one end connected to a positive electrode of a battery pack including a plurality of battery cells, a second main relay having one end connected to a negative electrode of the battery pack, and a battery management system, the battery management system comprising: closing the first main relay for a diagnostic period; measuring a positive electrode voltage of the battery pack and a negative link voltage of a second link wiring connected to the other end of the second main relay; comparing a voltage difference between the positive electrode voltage of the battery pack and the negative link voltage with a predetermined reference voltage; determining that there is an external short circuit when the voltage difference is less than the reference voltage. A method for diagnosing an external short circuit in a battery system.

7. The step of comparing the voltage difference with a predetermined reference voltage includes: The method for diagnosing an external short circuit in a battery system according to claim 6 , further comprising: comparing whether a voltage obtained by subtracting the negative link voltage from a positive electrode voltage of the battery pack is smaller than the reference voltage.

8. The method of claim 7, further comprising the step of multiplying a positive electrode voltage of the battery pack by a predetermined ratio to generate the reference voltage.

9. The method for diagnosing an external short circuit in a battery system according to claim 6 , further comprising the step of opening the second main relay during the diagnosis period.

10. The method of claim 6 , further comprising the step of opening a pre-charge relay connected in parallel to the first main relay during the diagnosis period.

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