Battery system

Abstract

The battery system (1) disclosed herein is equipped with two types of contactors, a first contactor (40) and a second contactor (50). The first contactor (40) is equipped with a first positive terminal (42) connected to the positive electrode (11Ap) of the battery unit (10) and a first negative terminal (44) connected to an external load (100) through a positive output terminal (20). Additionally, the second contactor (50) is equipped with a second positive terminal (52) connected to the negative electrode (11Nn) of the battery unit (10) and a second negative terminal (54) connected to an external load (100) through a negative output terminal (30). Furthermore, the battery system (1) disclosed herein is configured to prioritize turning off the contactor through which forward current flows, in either the charging or discharging phase. As a result, since the current can be cut off safely and quickly, failures caused by welding of the contactor can be prevented.

Description

Technology Field

[0001] The technology disclosed herein relates to a battery system. Background Technology

[0002] Battery systems using secondary batteries as a power source are used in various devices. This battery system is equipped with, for example, a battery unit having multiple secondary batteries and a pair of output terminals connecting the battery unit to a load of an external device (hereinafter referred to as "external load"). In this battery system, a contactor may be provided between the battery unit and the output terminals. The battery system switches the connection and disconnection between the battery unit and the external load by turning this contactor ON / OFF. Additionally, a standard contactor has polarity and is provided with a positive terminal and a negative terminal.

[0003] Japanese Patent Application Publication No. 2009-32551 discloses an example of a battery unit equipped with a contactor. The power supply device (battery system) described in this publication is characterized in that one of a pair of contactors is connected to a battery (battery unit) with the connection terminals of the positive and negative sides reversed. It is stated that according to the battery system of the above configuration, both the charging current and the discharging current can be rapidly cut off. Prior art literature

[0004] Japanese Application Publication No. 2009-32551 The problem to be solved

[0005] However, in the battery system described in the aforementioned Japanese Patent Publication No. 2009-32551, there was a risk that a failure would occur in which the contacts of the contactor would weld when the current was interrupted. The technology disclosed herein is designed to solve this problem. means of solving the problem

[0006] The battery system disclosed herein comprises a battery unit having a plurality of secondary batteries connected in series, a positive output terminal connecting the positive electrode of the battery unit to an external load, a negative output terminal connecting the negative electrode of the battery unit to an external load, a first contactor provided between the battery unit and the positive output terminal and having a positive terminal and a negative terminal, a second contactor provided between the battery unit and the negative output terminal and having a positive terminal and a negative terminal, a detection means for detecting whether the direction of current flowing between the battery unit and the external load is a discharge direction in which the battery unit is discharged or a charging direction in which the battery unit is charged, and a control device. In addition, the control device of the battery system disclosed herein comprises a cutting event acquisition unit that acquires that a cutting event has occurred in which it is necessary to cut off the battery unit and the external load by turning off both the first contactor and the second contactor, a determination unit that determines whether the direction of the current when the cutting event occurs is the discharge direction or the charge direction, and a cutting control unit that determines the order of turning off the first contactor and the second contactor based on the determination result of the determination unit. In addition, the cutting control unit is configured to prioritize turning off the contactor through which a forward current flows from the positive terminal to the negative terminal among the first contactor and the second contactor.

[0007] As described above, a conventional contactor has a positive terminal and a negative terminal. When current flows from the positive terminal to the negative terminal (hereinafter referred to as "forward current") within the contactor, the contactor can safely and quickly cut off the current. On the other hand, if the contactor is forcibly turned OFF while current flows from the negative terminal to the positive terminal (hereinafter referred to as "reverse current") within the contactor, there is a possibility that the contactor will overheat. At this time, if a large current flows through the contactor, there is a risk that the contacts of the contactor may weld due to rapid overheating. In contrast, the battery system disclosed herein is configured to determine whether the current direction at the time of a cutoff event is the discharge direction or the charge direction, and then to prioritize turning OFF the contactor through which the forward current flows from the positive terminal to the negative terminal. As a result, since the current can be cut off by the contactor safely and quickly, failures caused by welding of the contactor can be prevented. Brief explanation of the drawing

[0008] FIG. 1 is a circuit diagram illustrating a battery system according to a first embodiment. FIG. 2 is a flowchart showing a control procedure regarding a cutting event of a battery system according to a first embodiment. Figure 3 is a flowchart showing the detailed procedure of the current sensor fault determination process in Figure 2. FIG. 4 is a flowchart showing the determination procedure for a cutting event in the second embodiment. FIG. 5 is a flowchart showing the detailed procedure for determining a fault of a current sensor in the third embodiment. FIG. 6 is a circuit diagram illustrating a battery system according to a sixth embodiment. Specific details for implementing the invention

[0009] Embodiments of the technology disclosed herein are described below. Furthermore, matters other than those specifically mentioned in this specification and matters necessary for the implementation of the technology disclosed herein (e.g., detailed structure of battery units or external loads, components used in the construction of battery systems, etc.) may be understood as design matters by those skilled in the art based on prior art in the relevant field. The technology disclosed herein may be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field.

[0010] <First Embodiment>

[0011] 1. Components of the Battery System

[0012] Hereinafter, a first embodiment of the battery system disclosed herein will be described. FIG. 1 is a circuit diagram illustrating a battery system according to the first embodiment. The battery system (1) shown in FIG. 1 is connected to an external load (100). The external load (100) includes a general device that operates by power supply from the battery system (1). Although the technology disclosed herein is not limited, examples of the external load (100) include vehicle equipment, air conditioning equipment, residential equipment, cooking equipment, cleaning equipment, AV equipment, etc. Additionally, the external load (100) may be connected to the battery system (1) through an inverter or converter that adjusts the power supply voltage of the device.

[0013] In addition, the battery system (1) according to the present embodiment comprises a battery unit (10), a positive output terminal (20), a negative output terminal (30), a first contactor (40), a second contactor (50), a detection means (60), and a control device (70). Each component is described below.

[0014] (1) Battery unit

[0015] The battery unit (10) is a battery having a plurality of secondary batteries connected in series. In this specification, a single secondary battery is referred to as a "single cell." The battery unit (10) shown in FIG. 1 has a plurality (N) of single cells (11A to 11N). Here, the single cell placed at one end (upper side in FIG. 1) of the battery unit (10) is referred to as the "first single cell (11A)." Meanwhile, the single cell placed at the other end (lower side in FIG. 1) of the battery unit (10) is referred to as the "n-th single cell (11N)." In this battery unit (10), each of the plurality of single cells (11A to 11N) is electrically connected. However, the positive electrode (11Ap) of the first single cell (11A) is not connected to the other single cells. A total positive terminal (12) is connected to the positive electrode (11Ap) of this first single cell (11A). Meanwhile, the negative electrode (11Nn) of the nth single cell (11N) is not connected to any other single cell. A total negative terminal (14) is connected to the negative electrode (11Nn) of this nth single cell (11N). In addition, the number of single cells constituting the battery unit (10) is not particularly limited and can be appropriately changed considering the power required by the external load (100). For example, the number of single cells may be 50 or more, 75 or more, 90 or more, or 100 or more. In addition, the upper limit of the number of single cells is not particularly limited and may be 200 or less, or 150 or less.

[0016] (2) Positive output terminal

[0017] The positive output terminal (20) is a connecting member that connects the positive electrode (10p) of the battery unit (10) to an external load (100). Specifically, one end (22) of the positive output terminal (20) is connected to the positive electrode (11Ap) of the first battery (11A) through the first contactor (40) and the total positive terminal (12). Additionally, the other end (24) of the positive output terminal (20) is connected to the external load (100). Furthermore, the component for constructing the positive output terminal (20) is not particularly limited, and conventionally known conductive members (wires, bus bars, etc.) can be used.

[0018] (3) Negative output terminal

[0019] The negative output terminal (30) is a connecting member that connects the negative electrode (10n) of the battery unit (10) to an external load (100). Specifically, one end (32) of the negative output terminal (30) is connected to the negative electrode (11Nn) of the Nth single cell (11N) through the second contactor (50) and the total negative terminal (14). Additionally, the other end (34) of the negative output terminal (30) is connected to the external load (100). Furthermore, the component for constructing the negative output terminal (30) is not particularly limited, and a conductive member of the same type as the positive output terminal (20) can be used.

[0020] (4) First contactor

[0021] The first contactor (40) is a contactor provided between the battery unit (10) and the positive output terminal (20). As described above, the contactor has polarity and is provided with a positive terminal and a negative terminal. In this specification, the positive terminal of the first contactor (40) is referred to as the first positive terminal (42). Also, the negative terminal of the first contactor (40) is referred to as the first negative terminal (44). Furthermore, in this embodiment, the first positive terminal (42) of the first contactor (40) is connected to the positive terminal (10p) of the battery unit (10) (the positive terminal (11Ap) of the first single cell (11A)). Additionally, the first negative terminal (44) of the first contactor (40) is connected to an external load (100) through the positive output terminal (20). Additionally, the first contactor (40) is equipped with a first movable contact (46). When the first contactor (40) is ON, the first movable contact (46) contacts the first positive terminal (42) and the first negative terminal (44). By doing so, the positive terminal (10p) of the battery unit (10) and the external load (100) are connected. Meanwhile, when the first contactor (40) is OFF, the first movable contact (46) is separated from the first positive terminal (42) and the first negative terminal (44). By doing so, the conduction between the positive terminal (10p) of the battery unit (10) and the external load (100) is cut off.

[0022] (5) Second contactor

[0023] The second contactor (50) is a contactor provided between the battery unit (10) and the negative output terminal (30). In this specification, the positive terminal of the second contactor (50) is referred to as the second positive terminal (52). Additionally, the negative terminal of the second contactor (50) is referred to as the second negative terminal (54). In this embodiment, the second positive terminal (52) of the second contactor (50) is connected to the negative terminal (10n) of the battery unit (10) (the negative terminal (11Nn) of the Nth single battery (11N). Additionally, the second negative terminal (54) of the second contactor (50) is connected to an external load (100) through the negative output terminal (30). Furthermore, the second contactor (50) is provided with a second movable contact (56). When the second contactor (50) is ON, the second movable contact (56) contacts the second positive terminal (52) and the second negative terminal (54). By doing so, the negative electrode (10n) of the battery unit (10) and the external load (100) are connected. Meanwhile, when the second contactor (50) is OFF, the second movable contact (56) is separated from the second positive terminal (52) and the second negative terminal (54). By doing so, the conduction between the negative electrode (10n) of the battery unit (10) and the external load (100) is cut off.

[0024] (6) Detection means

[0025] The detection means (60) detects whether the direction of the current flowing between the battery unit (10) and the external load (100) is a discharge direction (D) in which the battery unit (10) is discharged, or a charging direction (C) in which the battery unit (10) is charged. Specifically, the “discharge direction (D)” in this specification is the direction of the current flowing from the positive electrode (10p) of the battery unit (10), through the first contactor (40), the positive electrode output terminal (20), the external load (100), the negative electrode output terminal (30), and the second contactor (50), to the negative electrode (10n) of the battery unit (10), as shown in FIG. 1. Meanwhile, "charging direction (C)" in this specification refers to the direction of current flowing from the negative electrode (10n) of the battery unit (10), through the second contactor (50), the negative electrode output terminal (30), the external load (100), the positive electrode output terminal (20), and the first contactor (40), to the positive electrode (10p) of the battery unit (10).

[0026] The detection means (60) is a device for detecting the current direction described above. For example, the detection means (60) is equipped with an external sensor and a judgment means for determining the current direction based on the detection result of said external sensor. For example, the judgment means may be built into the control device (70) described later, or it may be installed separately from the control device (70). Meanwhile, the external sensor may widely use a sensor capable of measuring parameters that can be used to determine the current direction. For example, the detection means (60) is a current value (I) flowing through the battery unit (10). aIt is preferable to have a current sensor (62) that detects the current. For example, the current sensor (62) is installed at the positive output terminal (20). In this case, a predetermined reference voltage (e.g., about 2.5V) is set in the judgment means of the detection means (60). If a voltage exceeding this reference voltage is detected by the current sensor (62), it can be determined that current is flowing in the discharge direction (D). On the other hand, if a voltage below the reference voltage is detected, it can be determined that current is flowing in the charging direction (C). Additionally, for the current sensor (62), for example, a Hall type or a shunt resistor type sensor may be used. Furthermore, as the current sensor (62), either an analog sensor that outputs a current value as an analog signal or a digital sensor that outputs a current value as a digital signal may be used.

[0027] Additionally, the external sensor of the detection means (60) is not limited to a current sensor (62) and only needs to be capable of acquiring information that can be used to determine the direction of the current. For example, a voltage sensor (64) that detects the voltage of the battery unit (10) may be used as the external sensor of the detection means (60). Specifically, when the battery system (1) is charging, the voltage of the battery unit (10) rises over time. Based on this, the judgment means of the detection means (60) can determine that the direction of the current is the charging direction (C). On the other hand, when the battery system (1) is discharging, the voltage of the battery unit (10) falls over time. In this case, the judgment means can determine that the direction of the current is the discharging direction (D).

[0028] (7) Control device

[0029] The control device (70) is a device that controls the charging and discharging of the battery unit (10). In addition, the control device (70) in this embodiment is configured to control the ON / OFF of the first contactor (40) and the second contactor (50). In addition, the control device (70) is connected to various sensors and can receive various information regarding the battery system (1). For example, the detection results of the current sensor (62) or the voltage sensor (64) are transmitted to the control device (70). This control device (70) is configured, for example, by a microcontroller. The control device (70) is equipped with a communication interface, a central processing unit (CPU) that executes commands of a control program, a read-only memory (ROM) that stores a program executed by the CPU, a random access memory (RAM) used as a working area for executing the program, and a memory such as a memory that stores the program and various data. The control device (70) is equipped with a cutting event acquisition unit (71), a judgment unit (72), and a cutting control unit (73). Additionally, the configuration within the control device (70) may be realized by one or more processors, or by a circuit. The configuration within the control device (70) will be described below.

[0030] (a) Cutting event acquisition section

[0031] The cutting event acquisition unit (71) acquires that a cutting event has occurred in which it is necessary to cut off the battery unit (10) and the external load (100) by turning off both the first contactor (40) and the second contactor (50). Here, "cutting event" refers to a state in which it is necessary to forcibly stop charging and discharging due to some abnormality. Examples of this cutting event include overcharging, over-discharging, overheating, and overcurrent. In the case of overcurrent, the cutting event acquisition unit (71) acquires the absolute value |I of the current value detected by the current sensor (62). a | is a predetermined threshold I th In the event of abnormalities, it is determined that a cutoff event has occurred. Below, a cutoff event caused by this overcurrent is explained as an example.

[0032] (b) Judgment panel

[0033] The determination unit (72) determines whether the current direction when a cutting event occurs is the discharge direction (D) or the charging direction (C). In the battery system (1) according to the present embodiment, the current direction detected by the detection means (60) is transmitted to the control device (70). When the cutting event acquisition unit (71) determines that a cutting event has occurred, the determination unit (72) determines whether the current current direction is the discharge direction (D) or the charging direction (C) by referring to the information from the detection means (60).

[0034] (c) Cutting control unit

[0035] The cutting control unit (73) determines the order in which the first contactor (40) and the second contactor (50) are turned OFF based on the judgment result of the judgment unit (72). Here, the cutting control unit (73) is configured to prioritize turning OFF the contactor through which the forward current flows from the positive terminal to the negative terminal among the first contactor (40) and the second contactor (50). In this embodiment, the cutting control unit (73) turns OFF the first contactor (40) first when the direction of the current is the discharge direction (D). Also, when the direction of the current is the charging direction (C), it turns OFF the second contactor (50) first. Although it will be described in detail later, by prioritizing turning OFF the contactor through which the forward current flows in this way, the current can be cut off by the contactor safely and quickly. As a result, failures caused by welding of the contactor can be prevented.

[0036] (d) Other configurations

[0037] In addition, the control device (70) according to the present embodiment is equipped with a limit determination unit (74) and a fault determination unit (75). The limit determination unit (74) has a threshold I of the cutting event acquisition unit (71). th The detection limit I, a current value greater than range is set. This limit determination unit (74) is the absolute value |I of the current value detected by the current sensor (62). a | Detection limit I range It determines whether there is an abnormality. And, the fault determination unit (75) determines the absolute value of the current value |I a | Detection limit I range In the event of an abnormality, a fault detection process for the current sensor (62) is performed. By adopting this configuration, it is possible to prevent forced cessation of charging and discharging in the event of a false detection caused by a fault in the current sensor (62).

[0038] Additionally, the control device (70) is equipped with a memory unit (79). Various information, such as the measurement results of the current sensor (62) or voltage sensor (64) and the charge / discharge history of the battery unit (10), is recorded in this memory unit (79). Furthermore, thresholds or reference values ​​used in various controls are also stored in the memory unit (79). It is preferable that the thresholds or reference values ​​within this memory unit (79) be configured so that the user can change them at will.

[0039] 2. Control method regarding cutting events

[0040] Hereinafter, a control method regarding a cutting event will be described in detail. FIG. 2 is a flowchart showing the control procedure regarding a cutting event of a battery system according to the present embodiment. FIG. 3 is a flowchart showing the detailed procedure for determining a fault of a current sensor in FIG. 2.

[0041] As illustrated in FIG. 2, the control method according to the present embodiment comprises a current value detection process S10, a cutting event determination process S20, a detection range determination process S30, a fault determination process S40, a current direction determination process S50, a first contactor cutting process S60, and a second contactor cutting process S70. Each process will be described below.

[0042] (1) Current value detection process S10

[0043] In this process, the current sensor (62) of the detection means (60) measures the current value (Ia) of the battery unit (10). Here, the current sensor (62) placed at the positive output terminal (20) detects a positive current value when the battery system (1) is charging and detects a negative current value when it is discharging. In this embodiment, the detection means (60) measures these current values ​​as an absolute value |I a It is converted into | and transmitted to the control device (70).

[0044] (2) Cutting event determination process S20

[0045] In this process, the cutting event acquisition unit (71) is the absolute value |I of the current value of the battery unit (10). a | and, a predetermined threshold I th Compares. And, the absolute value of the current |I a |Threshold I th If it is less than ("No" in S20), it is interpreted that no cutting event (an abnormality regarding overcurrent) occurs in the battery unit (10). In this case, the control device (70) terminates the control regarding the cutting event after giving instructions to continue charging and discharging (S22).

[0046] Meanwhile, the absolute value of the current |I a |Threshold I th In the case of an abnormality ("Yes" of S20), it can be determined that an abnormality regarding overcurrent has occurred in the battery system (1). In this case, the cutting event acquisition unit (71) notifies the limit determination unit (74) that a cutting event has occurred. Accordingly, the processing proceeds to the detection range determination process S30.

[0047] (3) Detection range determination process S30

[0048] In this process, the limit determination unit (74) determines the absolute value |I of the current value of the battery unit (10). a | and detection limit I range Compares. And, the absolute value of the current |I a | Detection limit I range If it is less than ("No" in S30), it can be determined that the current sensor (62) is normal. In this case, the limit determination unit (74) notifies the determination unit (72) that the notification of the occurrence of a cutting event by the cutting event acquisition unit (71) is appropriate. Accordingly, the processing proceeds to the current direction determination process S50.

[0049] Meanwhile, the absolute value of the current |I a | Detection limit I rangeIn the case of an abnormality (S30 "Yes"), there is a possibility that the current sensor (62) is faulty. In this case, the limit determination unit (74) detects the detection limit I range The fault determination unit (75) is notified of the occurrence of the above abnormality. Accordingly, the processing proceeds to the fault determination process S40.

[0050] (4) Fault determination process S40

[0051] In this process, the fault determination unit (75) determines whether the current sensor (62) is faulty. As illustrated in FIG. 3, in this fault determination process S40, first, it determines whether the current direction detected by the current sensor (62) is the charging direction (C) (S41). Here, if the current direction is the charging direction (C) (Yes in S41), the fault determination unit (75) determines whether a voltage rise is detected by the voltage sensor (64) (S42). Then, if a voltage rise is detected (Yes in S42), the fault determination unit (75) determines the amount of voltage rise (V r ) is the first voltage threshold (V th1 It determines whether it is greater than ) (S43). At this time, the voltage rise amount (V r ) is the first voltage threshold (V th1 If the value is greater than ) ("Yes" in S43), it is determined that the current sensor (62) is normal and overcharging has occurred. Meanwhile, if no voltage rise is detected by the voltage sensor (64) ("No" in S42), or if the amount of voltage rise (V r ) is the first voltage threshold (V th1 In the case where it is less than ("No" in S43), it is determined that overcharging has been detected even though no abnormal voltage rise has occurred. In this case, the fault determination unit (75) determines that the current sensor (62) is faulty.

[0052] Meanwhile, if the current direction is the discharge direction (D) ("No" in S41), the fault determination unit (75) determines whether a voltage drop has been detected by the voltage sensor (64) (S44). Then, if a voltage drop has been detected ("Yes" in S44), the amount of voltage drop (V d ) is the second voltage threshold (V th2 Determine whether it is less than or equal to ) (S45). And, the voltage drop amount (V d ) is the second voltage threshold (V th2 If it is less than ) ("Yes" in S45), it is determined that the current sensor (62) is normal and that over-discharge has occurred. Meanwhile, if a voltage drop is not detected by the voltage sensor (64) ("No" in S44), or if the amount of voltage drop (V d ) is the second voltage threshold (V th2 In the case where it exceeds ("No" in S45), it is determined that over-discharge is detected even though no abnormal voltage drop has occurred. In this case as well, it is determined that the current sensor (62) is faulty.

[0053] And, if it is determined that the current sensor (62) is faulty in the fault determination described above, the fault determination unit (75) notifies the cutting event acquisition unit (71) that the current sensor (62) is faulty (S49 in FIG. 2). In this case, the cutting event acquisition unit (71) cancels the occurrence of the cutting event, continues the charging and discharging of the battery unit (10), and then terminates the control regarding the cutting event. Meanwhile, if it is determined that the current sensor (62) is normal in the fault determination, the fault determination unit (75) notifies the determination unit (72) that the cutting event has occurred. Accordingly, the processing proceeds to the current direction determination process S50.

[0054] (5) Current direction determination process S50

[0055] In this process, the determination unit (72) determines whether the current direction is the discharge direction (D) or the charging direction (C) based on information transmitted from the detection means (60). Then, if the current direction is the discharge direction (D) ("Yes" in S50), the determination unit (72) transmits to the cutting control unit (73) that it is a cutting event during discharge and proceeds to the first contactor cutting process S60. On the other hand, if the current direction is the charging direction (C) ("No" in S50), the determination unit (72) transmits to the cutting control unit (73) that it is a cutting event during charging and proceeds to the second contactor cutting process S70.

[0056] (6) First contactor cutting process S60

[0057] As described above, the cutting control unit (73) in this embodiment is configured to first turn OFF the first contactor (40) when the direction of the current is the discharge direction (D). That is, when the cutting control unit (73) receives a signal that a cutting event has occurred during discharge, it transmits a cutting signal to the first contactor (40). Upon receiving the cutting signal, the first contactor (40) separates the first movable contact (46) from the first positive terminal (42) and the first negative terminal (44). By doing so, the first contactor (40) is turned OFF, and the discharge current is cut off. In this case, since the current in the discharge direction (D) is flowing, the forward current flows from the first contactor (40) and the reverse current flows from the second contactor (50). In this case, if the first contactor (40) is turned OFF first, the current can be cut off to the contactor through which the forward current flows, thereby preventing welding of the contactor due to rapid heating. Then, the cutting control unit (73) transmits a cutting signal to the second contactor (50) after turning the first contactor (40) OFF. By doing so, the second contactor (50) through which the reverse current flows can be safely cut.

[0058] (7) Second contactor cutting process S70

[0059] Meanwhile, in the present embodiment, the cutting control unit (73) first turns off the second contactor (50) when the direction of the current is the charging direction (C). That is, when it receives a notification that a cutting event has occurred during charging, the cutting control unit (73) transmits a cutting signal to the second contactor (50). Upon receiving the cutting signal, the second contactor (50) separates the second movable contact (56) from the second positive terminal (52) and the second negative terminal (54). By doing so, the second contactor (50) is turned off, and the charging current is cut off. When the current in the charging direction (C) flows in the opposite direction to the current in the discharge direction (D) described above, the current in the reverse direction flows from the first contactor (40), and the current in the forward direction flows from the second contactor (50). In the event of such a cutting event during charging, the second contactor (50) is turned OFF first, thereby blocking the current to the contactor through which the forward current flows, thus preventing welding of the contactor due to rapid heating. Then, the cutting control unit (73) transmits a cutting signal to the first contactor (40) after turning OFF the second contactor (50). By doing so, the first contactor (40) through which the reverse current flows can be safely cut.

[0060] As described above, the battery system (1) according to the present embodiment is configured such that when current flows in the discharge direction (D), a forward current flows through the first contactor (40), and when current flows in the charging direction (C), a forward current flows through the second contactor (50). Furthermore, the battery system (1) is configured such that when the discharge current is cut off, the first contactor (40) is turned OFF first, and when the charging current is cut off, the second contactor (50) is turned OFF first. That is, the battery system (1) according to the present embodiment is configured such that, in either charging or discharging, the contactor through which the forward current flows is turned OFF first. As a result, since the current cut off by the contactor can be safely and quickly performed, failures caused by welding of the contactor can be prevented. Consequently, since the contactor can be properly operated after the cut-off event ends, the battery system (1) can be quickly restarted. In addition, since unintended electrical conduction caused by welding of the contactor can be prevented, it can also contribute greatly to improving the safety of the battery system (1).

[0061] In addition, as described above, in the first contactor cutting process S60 or the second contactor cutting process S70, the contactor through which the forward current flows is turned OFF, and then the contactor through which the reverse current flows is turned OFF. At this time, the time difference (delay time) when turning OFF the two contactors is preferably 10 ms or more, more preferably 20 ms or more, and particularly preferably 30 ms or more. By doing so, the possibility of the contactor through which the reverse current flows being forcibly turned OFF can be more appropriately reduced. Meanwhile, the upper limit of the delay time is not particularly limited and may be 100 ms or less, 90 ms or less, or 80 ms or less.

[0062] <Other embodiments>

[0063] The first embodiment of the battery system disclosed herein has been described above. Furthermore, the above-described embodiment is not intended to limit the battery system disclosed herein. The technology disclosed herein includes other embodiments described below.

[0064] 1. Second embodiment

[0065] As described above, the battery system (1) according to the first embodiment targets a cutting event caused by overcurrent. Accordingly, in the battery system (1) according to the first embodiment, as shown in FIG. 2, the occurrence of overcurrent is determined in the current value detection process S10 to the fault determination process S40. However, the cause of the cutting event is not limited to the technology disclosed herein, and abnormalities other than overcurrent may be considered as the cutting event. As described above, other examples of causes of the cutting event include overcharging, over-discharging, and over-heating. In this case, as shown in FIG. 4, the control method regarding the cutting event is composed of a cutting event determination process S21, a current direction determination process S50, a first contactor cutting process S60, and a second contactor cutting process S70. In the control method shown in FIG. 4, in the cutting event determination process S21, the occurrence of the cause of the cutting event described above is determined. Then, if it is determined that a cutting event has occurred ("Yes" in S21), the current direction determination process S50 is performed in the same order as in the first embodiment to determine the order of cutting the contactor. Even with a control method configured in this way, since it is possible to prevent the contactor with reverse current flowing through it from being forcibly turned OFF, welding of the contactor due to rapid heating can be suppressed.

[0066] 2. Third embodiment

[0067] In addition, in the first embodiment, a fault determination process S40 is performed according to the procedure shown in FIG. 3. However, the fault determination process S40 is not limited to the procedure shown in FIG. 3. For example, the fault determination process S40 may be performed in the procedure shown in FIG. 5. In addition, to perform the fault determination process S40 shown in FIG. 5, it is necessary to install two current sensors in the conductive path of the battery unit (10). And in this third embodiment, in the detection range determination process S30 of FIG. 2, the absolute value |I of the current value measured by one current sensor (hereinafter referred to as "current sensor A") a-A | Detection limit I range In the case of an abnormality ("Yes" of S30), the fault determination process S40 illustrated in FIG. 5 is performed. In the fault determination process S40 illustrated in FIG. 5, first, it is determined whether the current direction detected by current sensor A is the charging direction (C) (S46). Here, if current sensor A detects the charging direction (C) ("Yes" of S46), the fault determination unit (75) [Q1]: the absolute value of the charging current measured by the other current sensor (hereinafter referred to as "current sensor B") |I a-B | Detection limit I range "Whether it is abnormal" and "Q2: Whether the current values ​​of current sensor A and current sensor B are approximate (|I a-A |≒|I a-B Two points are determined, such as "|)" (S47). If at least one of these two conditions is satisfied ("Yes" in S47), the fault determination unit (75) determines that current sensor A is normal because it can be assumed that the measured values ​​of both current sensor A and current sensor B are accurate. On the other hand, if neither of the conditions of step S47 is satisfied ("No" in S47), it can be determined that current sensor A is faulty.

[0068] Meanwhile, if the current direction detected by current sensor A is the discharge direction (D) ("No" in S46), the fault determination unit (75) [Q3: absolute value of the discharge current measured by current sensor B |I a-B | Detection limit I range "Whether it is abnormal" and "Q4: Whether the current values ​​of current sensor A and current sensor B are approximate (|I a-A |≒|I a-B Two points are determined, such as "|)" (S48). If at least one of these two conditions is satisfied ("Yes" in S48), the fault determination unit (75) determines that current sensor A is normal because it can be assumed that the measured values ​​of both current sensor A and current sensor B are accurate. On the other hand, if neither of the conditions of step S48 is satisfied ("No" in S48), it can be determined that current sensor A is faulty.

[0069] In addition, regarding the determination of the above Q2 and Q4, the current value |I of current sensor A a-A | and current value of current sensor B |I a-B The difference of | (|I a-A |-|I a-B When |) is within 20A (strictly speaking, within 10A, more strictly within 10A), it can be determined that the current values ​​of current sensor A and current sensor B are approximate. However, these figures are merely examples of criteria for determining "approximation" and do not limit the technology disclosed herein.

[0070] 3. Fourth embodiment

[0071] Additionally, it is preferable that the control device (70) of the battery system (1) be configured to transmit information regarding a cutting event acquired by the cutting event acquisition unit (71) to an external control unit (not shown) that controls the external load (100). Furthermore, it is preferable that the external control unit of the external load (100) control the operation of the external load (100) based on information regarding the cutting event before the cutting control unit (73) of the battery system (1) performs the cutting of the contactor. For example, when information regarding an overcurrent occurrence is received from the battery system (1), the external control unit controls the operation of the external load (100) so that the overcurrent is resolved. By doing so, since there is a possibility of resolving the cutting event before the forced cutting of the contactor, the deterioration of the contactor caused by the forced cutting of the current can be more effectively prevented. And, if the cutting control unit (73) of the battery system (1) is unable to resolve the cutting event by controlling the external load (100), it may turn off the contactor according to the above procedure. By doing so, the cutting event can be resolved more safely.

[0072] 4. Fifth embodiment

[0073] As described above, in the current value detection process S10 of the first embodiment, the current value (positive current value, negative current value) measured by the current sensor (62) is detected by the detection means (60) as an absolute value |I a It is converted into | and used for determination in the cutting event acquisition unit (71). However, this conversion to an absolute value is not limited to the technology disclosed herein. The detection means (60) may transmit the current value (positive current value, negative current value) measured by the current sensor (62) directly to the cutting event acquisition unit (71). In this case, the cutting event acquisition unit (71) has a threshold I for the positive current value. th1 Threshold I for positive and negative current values th2 of Two types of thresholds are set. And, when a positive current value is received, the cutting event acquisition unit (71) detects that the detection result of the current sensor (62) is a positive threshold I th1 It determines whether there is an abnormality. Meanwhile, if a negative current value is received, the cutting event acquisition unit (71) determines that the detection result of the current sensor (62) is a negative threshold I th2 Determines whether it is less than or equal to. Even when this configuration is adopted, the absolute value |I a Even without performing a conversion to |, the occurrence of a truncation event can be determined.

[0074] 5. Sixth embodiment

[0075] The first to fifth embodiments are based on a battery system (1) with the configuration shown in FIG. 1. However, the technology disclosed herein also includes a configuration in which the connection direction of the first contactor and the second contactor is reversed from the configuration shown in FIG. 1. FIG. 6 is a circuit diagram illustrating a battery system according to the sixth embodiment. In the battery system (1A) according to this sixth embodiment, the first negative terminal (44) of the first contactor (40) is connected to the positive electrode (10p) of the battery unit (10). Meanwhile, the first positive terminal (42) of the first contactor (40) is connected to an external load (100) through a positive output terminal (20). Meanwhile, the second negative terminal (54) of the second contactor (50) is connected to the negative electrode (10n) of the battery unit (10). And, the second positive terminal (52) of the second contactor (50) is connected to an external load (100) through the negative output terminal (30). When adopting a battery system (1A) with this configuration, the cutting control unit (73) first turns off the second contactor (50) when the direction of the current is the discharge direction (D), and also turns off the first contactor (40) when the direction of the current is the charge direction (C). By doing so, even if the connection direction of the first contactor (40) and the second contactor (50) is reversed, the contactor through which the forward current flows can be turned off first.

[0076] Although the technology disclosed herein has been described in detail, these are merely examples and do not limit the scope of the patent claims. The technology described in the patent claims includes various modifications and alterations of the specific examples exemplified above. Explanation of the symbols

[0077] 1: Battery System 10: Battery unit 11A to 11N: Multiple single cells 20: Positive output terminal 30: Negative output terminal 40: 1st contactor 42: 1st positive terminal 44: 1st negative terminal 46: First movable contact 50: Second contactor 52: Second positive terminal 54: Second negative terminal 56: Second movable contact 60: Detection means 70: Control unit 71: Cutting Event Acquisition Section 72: Judgment panel 73: Cutting control unit 74: Limit determination unit 75: Fault determination unit 79: Memory Department 100: External load

Claims

Claim 1 A battery unit having a plurality of secondary batteries connected in series, a positive output terminal connecting the positive electrode of the battery unit to an external load, a negative output terminal connecting the negative electrode of the battery unit to the external load, a first contactor provided between the battery unit and the positive output terminal and having a positive terminal and a negative terminal, a second contactor provided between the battery unit and the negative output terminal and having a positive terminal and a negative terminal, a detection means for detecting whether the direction of current flowing between the battery unit and the external load is a discharge direction in which the battery unit is discharged or a charging direction in which the battery unit is charged, and a control device are provided, wherein the control device comprises a cutting event acquisition unit that acquires that a cutting event has occurred in which it is necessary to cut the battery unit and the external load by turning off both the first contactor and the second contactor, a determination unit that determines whether the direction of the current when the cutting event occurs is the discharge direction or the charging direction, and based on the determination result of the determination unit, the first contactor and the second contactor A battery system comprising a cutting control unit for determining the order of turning off, wherein the cutting control unit is configured to preferentially turn off the contactor through which a forward current flows from the positive terminal to the negative terminal among the first contactor and the second contactor. Claim 2 A battery system according to claim 1, wherein the first contactor comprises a first positive terminal connected to the positive electrode of the battery unit and a first negative terminal connected to the external load through the positive output terminal, and the second contactor comprises a second positive terminal connected to the negative electrode of the battery unit and a second negative terminal connected to the external load through the negative output terminal, and the cutting control unit is configured to first turn OFF the first contactor when the direction of the current is the discharge direction, and also to first turn OFF the second contactor when the direction of the current is the charging direction. Claim 3 A battery system according to claim 1 or 2, wherein the detection means comprises a current sensor that detects a current value flowing through the battery unit. Claim 4 In paragraph 3, the cutting event acquisition unit determines that the cutting event has occurred when the current value detected by the current sensor is greater than or equal to a predetermined threshold, in a battery system. Claim 5 In claim 4, the control device comprises a detection limit that is greater than the threshold set in the cutting event acquisition unit, a limit determination unit that determines whether the absolute value of the current value detected by the current sensor is greater than the detection limit, and a fault determination unit that executes a fault determination process of the current sensor when the absolute value of the current value is greater than the detection limit. Claim 6 In claim 5, the above-mentioned cutting event acquisition unit determines that the cutting event has occurred when it is determined by the above-mentioned fault determination process that no fault has occurred in the above-mentioned current sensor, in a battery system. Claim 7 In paragraph 5, the battery system, wherein the control device executes a predetermined fault treatment when it is determined by the fault determination process that a fault has occurred in the current sensor.

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