protection circuit

Abstract

A protection circuit (1A) includes a protection element (10A), a plurality of secondary battery cells (20), (20),..., an external positive terminal (30a) and an external negative terminal (30b), an auxiliary power supply (40), a first control device (50), and a switch (60). The protection element (10A) includes a first fusible conductor (15) having both ends connected to a first terminal (11) and a second terminal (12), and a heat generator (16) provided in a first current path (P1 A ) between a third terminal (13) and a fourth terminal (14). The auxiliary power supply (40) is electrically independent from the plurality of secondary battery cells (20), (20),.... In the protection circuit (1A), the switch (60) is switched to be energized according to a signal from the first control device (50), the heat generator (16) of the protection element (10A) generates heat, the first fusible conductor (15) is fused, and the plurality of secondary battery cells (20), (20),... are cut off from the external negative terminal (30b).

Description

Technical Field

[0001] This invention relates to protection circuits, such as protection circuits provided in the charging and discharging circuits of secondary batteries.

[0002] This application claims priority based on Japanese Patent Application No. 2020-094274 filed on May 29, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] Lithium-ion batteries are widely used as power sources for mobile devices such as laptops. The protection circuits of secondary batteries, such as lithium-ion batteries, include a self-control protector (SCP) with a surface-mount heater. In the event of an overvoltage anomaly, the secondary battery itself supplies power to the heater, causing it to heat up and melt the fuse element.

[0004] For example, as an existing protection circuit, such as Figure 13 (a) and Figure 13 As shown in (b), there is a protection circuit 100 comprising: SCP 110 having fuse elements 111, 111 connected to the power path and a heater 112 connected to the fuse elements 111, 111 and capable of melting by heating the fuse elements 111, 111; IC 130, which detects abnormalities in the battery cells 121, 121, ... of the battery 120 connected to the power path; FET 140, which operates to energize the heater 112 of SCP 110 according to the detection result of IC 130; IC 150, which detects abnormalities in the battery 120 as a whole; and FETs 160, 160, which operate to energize the heater 112 of SCP 110 according to the detection result of IC 150. In the protection circuit 100, if an abnormality is detected in any of the battery cells, FET 140 is turned on, supplying power from battery 120 to heater 112 of SCP 110 to generate heat, and fuse element 111 blows.

[0005] In addition, as other conventional protection circuits, a protection circuit has been proposed that configures a fusible conductor (fuse element) between the data server and the Internet line, and has a heating element and an external power supply dedicated to the heating element that are set independently of the aforementioned fusible conductor (Patent Document 1).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-46316 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the Figure 13 When conventional protection circuits, such as those in (a), are installed in the charging and discharging circuits of high-capacity secondary batteries used for power applications, there is a problem where the heater is damaged due to the high voltage and high current of varying orders of magnitude. Recently, lithium-ion batteries, as secondary batteries, have expanded from applications in mobile devices to EVs, rechargeable batteries, and other applications, and are undergoing a process of increasing capacity. Furthermore, with the increasing capacity of lithium-ion batteries, voltages have reached hundreds of volts, and currents have reached hundreds of amperes, requiring highly safe protection circuits to meet these demands.

[0011] In the protection circuit of Patent Document 1, regardless of the type of external circuit such as a data server, sufficient power to generate enough heat to melt the fusible conductor can be supplied to the heating element, making it applicable to digital signal circuits that carry weak currents as external circuits. That is, Patent Document 1 discloses a structure for applying a protection circuit to signal circuits to prevent information leakage caused by hackers, but does not disclose or suggest applying the protection circuit to the charging and discharging circuit of a secondary battery used for power purposes. Furthermore, while the aforementioned protection circuit is considered applicable to low-voltage specifications of tens of volts, it is difficult to ensure the voltage withstand capability of the heating element and the insulation after the fusible conductor is cut in cases of high voltage and high current specifications such as hundreds of volts and hundreds of amperes. Therefore, it is difficult to apply the aforementioned protection circuit to the charging and discharging circuit of a high-capacity secondary battery.

[0012] The purpose of this invention is to provide a protection circuit that can reliably cut off the charging and discharging circuit of a secondary battery to achieve high safety.

[0013] Methods for solving problems

[0014] To achieve the above objectives, the present invention provides the following means.

[0015] [1] A protection circuit, comprising:

[0016] A protective element having a first terminal, a second terminal, a first fusible conductor with its two ends connected to the first terminal and the second terminal, a third terminal, a fourth terminal, and a heating element disposed on a first energizing path between the third terminal and the fourth terminal;

[0017] Multiple secondary battery cells connected in series;

[0018] External positive end and external negative end;

[0019] An auxiliary power supply is configured to be electrically independent of the plurality of secondary battery cells;

[0020] a control device that monitors voltages of the plurality of secondary battery cells, detects abnormality, and outputs a signal; and

[0021] a switch that switches power supply in response to the signal from the control device,

[0022] the control device is connected to the plurality of secondary battery cells,

[0023] the first terminal and the second terminal of the protection element are provided in a second power supply path between positive terminals of the plurality of secondary battery cells and the external positive terminal or between negative terminals of the plurality of secondary battery cells and the external negative terminal,

[0024] the third terminal and the fourth terminal of the protection element are connected in series with the auxiliary power supply and the switch and are connected in a ring shape,

[0025] the protection element is switched to the switch in response to the signal from the control device, the heat generator of the protection element generates heat, the first fusible conductor is fused, and the plurality of secondary battery cells and the external positive terminal or the plurality of secondary battery cells and the external negative terminal are cut off.

[0026] [2] The protection circuit according to the above [1], wherein a second fusible conductor is provided between the heat generator of the protection element and the third terminal or between the heat generator of the protection element and the fourth terminal.

[0027] [3] The protection circuit according to the above [1], wherein a second fusible conductor is provided between the heat generator of the protection element and the third terminal and a third fusible conductor is provided between the heat generator and the fourth terminal.

[0028] [4] A protection circuit comprising:

[0029] a protection element having a first terminal, a second terminal, a first fusible conductor connected between the first terminal and the second terminal, a third terminal, a fourth terminal, and a heat generator provided in a first power supply path between the third terminal and the fourth terminal;

[0030] a plurality of secondary battery cells connected in series;

[0031] an external positive terminal and an external negative terminal;

[0032] an auxiliary power supply;

[0033] a control device that monitors voltages of the plurality of secondary battery cells, detects abnormality, and outputs a signal; and

[0034] a switch that switches power supply in response to a signal from the control device,

[0035] the control device is connected to the plurality of secondary battery cells,

[0036] the first terminal and the second terminal of the protection element are provided in a second power supply path between a positive electrode terminal of the plurality of secondary battery cells and the external positive electrode terminal or between a negative electrode terminal of the plurality of secondary battery cells and the external negative electrode terminal,

[0037] the third terminal and the fourth terminal of the protection element are connected in series with the auxiliary power supply and the switch and connected in a ring shape,

[0038] the second power supply path in which the first terminal and the second terminal of the protection element are connected is connected to a third power supply path in which the third terminal is connected to the fourth terminal via the auxiliary power supply and the switch,

[0039] the switch is switched to supply power in response to the signal from the control device, the heat generator of the protection element generates heat, the first fusible conductor is fused, and the plurality of secondary battery cells and the external positive electrode terminal or the plurality of secondary battery cells and the external negative electrode terminal are disconnected.

[0040] [5] The protection circuit according to the above [4], wherein a second fusible conductor is provided between the heat generator of the protection element and the third terminal or between the heat generator of the protection element and the fourth terminal.

[0041] [6] The protection circuit according to the above [4], wherein a second fusible conductor is provided between the heat generator of the protection element and the third terminal and a third fusible conductor is provided between the heat generator and the fourth terminal.

[0042] [7] A protection circuit comprising:

[0043] a protection element having a first terminal, a second terminal, a first fusible conductor connected between both terminals and the first terminal and the second terminal, a third terminal, and a heat generator provided in a first power supply path between the third terminal and the first terminal or the second terminal;

[0044] a plurality of secondary battery cells connected in series;

[0045] an external positive electrode terminal and an external negative electrode terminal;

[0046] an auxiliary power supply;

[0047] a control device that monitors a voltage of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; and

[0048] a switch that switches power supply in response to a signal from the control device,

[0049] the control device is connected to the plurality of secondary battery cells,

[0050] the first terminal and the second terminal of the protection element are provided in a second power supply path between positive terminals of the plurality of secondary battery cells and the external positive terminal or between negative terminals of the plurality of secondary battery cells and the external negative terminal,

[0051] the third terminal of the protection element is connected to the second power supply path in which the first terminal and the second terminal of the protection element are connected via the auxiliary power supply and the switch,

[0052] in response to the signal from the control device, the switch switches power supply, the heat generator of the protection element generates heat, the first fusible conductor is fused, and the plurality of secondary battery cells and the external positive terminal or the plurality of secondary battery cells and the external negative terminal are disconnected.

[0053] [8] The protection circuit according to the above [7], wherein a second fusible conductor is provided between the heat generator and the third terminal of the protection element.

[0054] [9] The protection circuit according to the above [7], wherein a second fusible conductor is provided between the heat generator and the third terminal of the protection element, and a third fusible conductor is provided between the heat generator and the first terminal or the second terminal.

[0055]

[10] The protection circuit according to any one of the above [4] to [9], wherein the poles of the second power supply path in which the first terminal and the second terminal of the protection element are connected and the pole of the auxiliary power supply connected to one side of the third terminal are connected in a same-pole manner.

[0056]

[11] The protection circuit according to any one of the above [4] to

[10] , wherein the first fusible conductor is a laminate including a low-melting-point metal layer and a high-melting-point metal layer.

[0057]

[12] The protection circuit according to the above

[11] , wherein the low-melting-point metal layer is composed of Sn or an alloy in which Sn is a main component, and the high-melting-point metal layer is composed of Ag or Cu or an alloy in which Ag or Cu is a main component.

[0058] Effects of the Invention

[0059] According to the present application, the charge-discharge circuit of the secondary battery can be reliably cut off, and high safety can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 (a) of FIG. 1 is a circuit diagram schematically showing an example of the structure of the protection circuit of the first embodiment of the present application, Figure 1 (b) of FIG. 1 is a diagram schematically showing an example of the structure of the protection element.

[0061] Figure 2 (a) of FIG. 2 and Figure 2 (b) of FIG. 2 are diagrams showing Figure 1 (b) of FIG. 2 is a sectional view showing an example of the structure of the protection element of (b) of FIG. 2.

[0062] Figure 3 (a) of FIG. 3 and Figure 3 (b) of FIG. 3 are diagrams showing Figure 1 (a) of FIG. 3 and Figure 1 (b) of FIG. 3 are diagrams showing modification examples of the protection circuit of (a) of FIG. 3 and the protection element of (b) of FIG. 3.

[0063] Figure 4 (a) of FIG. 4 and Figure 4 (b) of FIG. 4 are diagrams showing Figure 1 (a) of FIG. 4 and Figure 1 (b) of FIG. 4 are diagrams showing other modification examples of the protection circuit of (a) of FIG. 4 and the protection element of (b) of FIG. 4.

[0064] Figure 5 (a) of FIG. 5 is a circuit diagram schematically showing an example of the structure of the protection circuit of the second embodiment of the present application, Figure 5 (b) of FIG. 5 is a diagram schematically showing an example of the structure of the protection element.

[0065] Figure 6 (a) of FIG. 6 and Figure 6 (b) of FIG. 6 are diagrams showing Figure 5 (a) of FIG. 6 and Figure 5 (b) of FIG. 6 are diagrams showing modification examples of the protection circuit of (a) of FIG. 6 and the protection element of (b) of FIG. 6.

[0066] Figure 7 (a) of FIG. 7 and Figure 7 (b) of FIG. 7 are diagrams showing Figure 5 (a) of FIG. 7 and Figure 5 (b) of FIG. 7 are diagrams showing other modification examples of the protection circuit of (a) of FIG. 7 and the protection element of (b) of FIG. 7.

[0067] Figure 8 (a) of FIG. 8 is a circuit diagram schematically showing an example of the structure of the protection circuit of the third embodiment of the present application, Figure 8 (b) of FIG. 8 is a diagram schematically showing an example of the structure of the protection element.

[0068] Figure 9 (a) of FIG. 8 andFigure 9 (a) of FIG. 1 is a circuit diagram schematically showing an example of the structure of the protection circuit of the first embodiment of the present application. Figure 8 (a) of FIG. 1 and Figure 8 (b) of FIG. 1 is a modification example of the protection circuit of (a) of FIG. 1 and

[0069] Figure 10 (a) of FIG. 1 and Figure 10 (b) of FIG. 1 is a modification example of the protection circuit of (a) of FIG. 1 and Figure 8 (a) of FIG. 1 and Figure 8 (b) of FIG. 1 is a modification example of the protection circuit of (a) of FIG. 1 and

[0070] Figure 11 (a) of FIG. 1 and

[0071] Figure 12 (a) of FIG. 1 and Figure 8 (b) of FIG. 1 is a modification example of the protection circuit of (a) of FIG. 1 and

[0072] Figure 13 (a) of FIG. 1 and Figure 13 (b) of FIG. 1 is a modification example of the protection circuit of (a) of FIG. 1 and DETAILED DESCRIPTION

[0073] Hereinafter, the embodiments of the present application will be described in detail with reference to the accompanying drawings. In the drawings used in the following description, in order to easily understand the features, sometimes the portions to be features are enlarged and shown for the convenience, and the size ratio and the like of each constituent element are sometimes different from the actual. The materials, dimensions, and the like exemplified in the following description are one example, and the present application is not limited thereto, and can be implemented by being appropriately changed within the range where the effects of the present application are exerted.

[0074] Figure 1 (a) of FIG. 1 is a circuit diagram schematically showing an example of the structure of the protection circuit of the first embodiment of the present application.

[0075] (a) of FIG. 1 is a circuit diagram schematically showing an example of the structure of the protection circuit of the first embodiment of the present application. Figure 1As shown in (a), the protection circuit 1A includes a protection element 10A, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50 (control device), and a switch 60. The multiple secondary battery cells 20, 20, ... are connected in series. The positive terminal 20a of the multiple secondary battery cells 20, 20, ... is connected to the external positive terminal (described later), and the negative terminal 20b is connected to the external negative terminal (described later). The multiple secondary battery cells 20, 20, ... are secondary batteries, such as lithium-ion secondary batteries. The total voltage of the multiple secondary battery cells 20, 20, ... is at least 100V or more in the case of battery applications, and for example, 350V or more and 800V or less in the case of EV applications. The protection circuit 1A has external positive terminals 30a and external negative terminals 30b, which are connected to an external charging device.

[0076] like Figure 1 As shown in (b), the protection element 10A has a first terminal 11, a second terminal 12, a first fusible conductor 15 connected at both ends to the first terminal 11 and the second terminal 12, a third terminal 13, a fourth terminal 14, and a first energizing path P1 disposed between the third terminal 13 and the fourth terminal 14. A The heating element 16. In this embodiment, the first terminal 11 and the second terminal 12 of the protection element 10A are disposed in the second power path P2 between the negative terminals 20b of the plurality of secondary battery cells 20, 20, ... and the external negative terminal 30b. A Additionally, the third terminal 13 and the fourth terminal 14 of the protection element 10A are connected in series with the auxiliary power supply 40 and the switch 60, forming a loop.

[0077] The first fusible conductor 15 is, for example, constituted by a fuse element housed in a housing (not shown). The fuse element is, for example, sheet-like or rod-like. One end 15a of the first fusible conductor 15 is connected to the first terminal 11, and the other end 15b is connected to the second terminal 12.

[0078] The first fusible conductor 15 is preferably a laminate including a low melting point metal layer and a high melting point metal layer composed of a high melting point metal having a higher melting point than the low melting point metal. Further, the first fusible conductor 15 is more preferably provided with a covering structure composed of a low melting point metal layer as an inner layer and a high melting point metal layer as an outer layer covering the low melting point metal layer as the inner layer. For example, the first fusible conductor 15 can also be a laminate of a 3-layer structure in which an inner layer and an outer layer sandwiching the inner layer are laminated in the thickness direction, the inner layer and the outer layer being composed of materials having different softening temperatures. In such a first fusible conductor 15, in the inner layer and the outer layer of the laminate, the mixed state of the solid phase and the liquid phase first starts in the layer of the material having a lower softening temperature, and can be cut off before the layer of the material having a higher softening temperature reaches the softening temperature.

[0079] The low melting point metal layer is composed of, for example, Sn or an alloy in which Sn is a main component. Sn has a melting point of 232°C, and thus a metal in which Sn is a main component is low in melting point and becomes soft at a low temperature. For example, the Sn / Ag 3% / Cu 0.5% alloy has a solidus of 217°C. Further, as the material constituting the low melting point metal layer, various low melting point metals that have been used as fuse materials can be used. As the low melting point metal, SnSb alloy, BiSnPb alloy, BiPbSn alloy, BiPb alloy, BiSn alloy, SnPb alloy, SnAg alloy, SnAgCu alloy, PbIn alloy, ZnAl alloy, InSn alloy, PbAgSn alloy, and the like can be given.

[0080] The material constituting the high melting point metal layer is composed of, for example, Ag or Cu, or an alloy in which Ag or Cu is a main component. Ag has a melting point of 962°C, and copper has a melting point of 1085°C, and thus a layer composed of a metal in which Ag or Cu is a main component maintains rigidity at a temperature at which a layer composed of a low melting point metal becomes soft.

[0081] The heat generating body 16 is a plate-like member, and has, for example, an insulating substrate and a heat generating portion formed on the insulating substrate. The heat generating body 16 is disposed, for example, in abutment with the first fusible conductor 15 or directly above the first fusible conductor 15. In this case, the heat generating body 16 preferably has a function of heating the first fusible conductor 15 to soften it, and a function of imparting a pressing force of a pressing unit described later to the first fusible conductor 15 to cut the first fusible conductor 15.

[0082] As the insulating substrate, a publicly known substrate having insulating properties can be used, and for example, a substrate composed of alumina, glass ceramic, mullite, zirconia, or the like can be given.

[0083] The aforementioned heating element is preferably a resistive element made of a conductive material that generates heat when electricity is applied. Examples of materials for the heating element include those containing metals such as nickel-chromium alloy, W, Mo, and Ru. This heating element is formed, for example, by coating a resistive paste composed of conductive materials such as ruthenium oxide and carbon black, inorganic binders such as water glass, and organic binders such as thermosetting resins, and then firing it as needed. Alternatively, the heating element can be formed by printing, plating, vapor deposition, sputtering, or by bonding or laminating these films.

[0084] Figure 2 (a) and Figure 2 (b) means Figure 1 (b) A cross-sectional view of the structure of the protective element 10A. Figure 2 (a) and Figure 2 The structure of the protective element 10A in (b) is shown as an example, but the structure of the protective element of the present invention is not limited thereto.

[0085] like Figure 2 As shown in (a), the protective element 10A includes: a fuse element (first fusible conductor) 2 having a cut-off portion 2c between one end 2a and the other end 2b; a movable member 3 having a heating element 3a and a convex member 3b; a concave member 4; a pressing unit 5; and a housing 6.

[0086] One end 2a of the fuse element 2 is connected to the first terminal 6a by welding or the like, and the other end 2b is connected to the second terminal 6b by welding or the like. One end of the heating element 3a is connected to a third terminal (not shown), and the other end is connected to a fourth terminal (not shown). The convex member 3b has the function of applying the pressing force of the pressing unit 5 to the cutting portion 2c of the fuse element 2, and the convex portion 3c of the convex member 3b is pressed against the heating element 3a. The concave member 4 is arranged opposite to the movable member 3 and cooperates with the movable member 3 to clamp the cutting portion 2a of the fuse element 2. The concave portion 4a of the concave member 4 is formed to accommodate the convex portion 3c of the heating element 3a. The pressing unit 5 applies force to the movable member 3, such that the movable member 3 and the concave member 4 clamp the cutting portion 2c, and shorten the relative distance between these members when the cutting portion 2a is cut. As the pressing unit 5, for example, a spring is used to maintain a restoring force in the Z direction and is accommodated between the convex member 3b and the housing 6.

[0087] In this protective element 10A, when the heating element 3a of the movable part 3 heats up, the fuse element 2 softens at a temperature above its softening temperature. Simultaneously, due to the pressing force of the pressing unit 5, the protrusion 3c of the convex part 3b enters the recess 4a of the concave part 4. As a result, the cutting part 2c disconnects from one end 2a (or the other end 2b), and the fuse element 2 is cut off. Figure 2 (b)

[0088] The auxiliary power supply 40 is provided independently of the plurality of secondary battery cells 20, 20,.... The auxiliary power supply 40 is not particularly limited as long as it is configured to supply electric power capable of fusing the first fusible conductor 15 at the time of energization, and is constituted by, for example, a primary battery or a secondary battery, or the like. As the secondary battery, for example, a lead storage battery, a lithium ion battery, or the like can be given. The voltage of the auxiliary power supply is, for example, 10 V or more and 56 V or less.

[0089] The first control device 50 is connected to the plurality of secondary battery cells 20, 20,..., monitors one or more voltages of the plurality of secondary battery cells 20, 20,..., detects an abnormality, and outputs a signal. The first control device 50 is, for example, an IC, detects the second energization path P2 of the protection element 10A, and outputs a signal to the switch 60. A The voltage of each of the plurality of secondary battery cells 20, 20,... connected is based on the voltage to determine whether an abnormality such as overcharge has occurred in the plurality of secondary battery cells 20, 20,.... In the case where an abnormality has occurred in the plurality of secondary battery cells 20, 20,..., the first control device 50 cuts off the energization path by causing the protection element 10A to operate.

[0090] The switch 60 switches energization in response to the signal of the first control device 50. The switch 60 is not particularly limited, and is, for example, a field effect transistor (hereinafter, also referred to as an FET). As the FET, there is no particular limitation, and, for example, a junction FET, a MOS FET, or the like can be used. In the present embodiment, the gate of the FET is connected to the first control device 50, and the drain is connected to the heat generator 16. The switch 60 performs on or off operation in accordance with the control signal output from the first control device 50.

[0091] In the present embodiment, the protection circuit 1A further includes a second control device 80 and switches 90, 90. The second control device 80 is, for example, an IC, monitors the voltage of the entire plurality of secondary battery cells 20, 20,..., detects an abnormality, and outputs a signal. The switches 90, 90 switch energization in response to the signal of the second control device 80. The switches 90, 90 are not particularly limited, and are, for example, FETs. The protection circuit 1A preferably includes the second control device 80 and the switches 90, 90, but can not include them.

[0092] In the protection circuit 1A configured as described above, when the plurality of secondary battery cells 20, 20,... are charged, electric power is supplied from the charging device to the plurality of secondary battery cells 20, 20,... via the external circuit. In addition, when the plurality of secondary battery cells 20, 20,... are discharged, electric power is supplied from the plurality of secondary battery cells 20, 20,... to the external circuit. The external circuit is connected to, for example, a load such as a motor, a converter, or the like, which is not shown.

[0093] In the protection circuit 1A, the heating body 16 of the protection element 10 is heated, the first fusible conductor 15 is fused, and the plurality of secondary battery cells 20, 20,... and the external negative terminal 30b are cut off by switching the switch 60 to be energized according to a signal from the first control device 50. Specifically, the first control device 50 detects the voltage of each of the plurality of secondary battery cells 20, 20,..., and when it is determined that the voltage of any one or more of the plurality of secondary battery cells 20, 20,... deviates from a predetermined value indicating an overdischarge or overcharge state, a control signal is output to the switch 60. Further, the switch 60 on the first energization path P1 A is turned on, and the heating body 16 is supplied with electric power from the auxiliary power supply 40, and the heating body 16 is heated. By the heat of the heating body 16, the first fusible conductor 15 on the second energization path P2 A is fused, and thus the energization path of the protection circuit 1A is cut off.

[0094] As described above, according to the present embodiment, by making the second energization path P2 A in which the plurality of secondary battery cells 20, 20,... are connected via the first fusible conductor 15 and the first energization path P1 A in which the heating body 16 and the auxiliary power supply 40 are connected independent structures, it is possible to appropriately select the specifications of the heating body 16 in the first energization path P1 A . Therefore, even in the case where a large voltage and a large current occur in the second energization path P2 A , by reducing the voltage applied to the heating body 16 in the first energization path P1 A , it is possible to sufficiently ensure the withstand voltage, and as a result, it is possible to reliably cut off the charge-discharge circuit of the plurality of secondary battery cells 20, 20,..., and achieve high safety. In particular, even in the case where an unexpected accident or a natural disaster or the like occurs when a vehicle such as an electric vehicle is used, it is possible to prevent electric shock caused by the charge-discharge circuit of the plurality of secondary battery cells 20, 20,...

[0095] Further, the first terminal 11 and the second terminal 12 of the protection element 10A are provided on the second energization path P2 A between the negative terminals 20b of the plurality of secondary battery cells 20, 20,... and the external negative terminal 30b, the third terminal 13 and the fourth terminal 14 of the protection element 10A are connected in series with the auxiliary power supply 40 and the switch 60 and connected in a ring shape, and thus it is possible to reliably apply only the voltage of the auxiliary power supply 40 to the heating body 16. Therefore, in the charge-discharge circuit for power of an electric vehicle or the like in which a large-capacity lithium ion battery of several hundred volts (for example, 350 V or more) is mounted, it is possible to construct a protection circuit with high safety.

[0096] Figure 3 (a) is a view showing Figure 1The circuit diagram of a modified example of the protection circuit 1A of (a). Figure 3 The protection circuit 1B of (a) is similar to the protection element 10B in that it replaces the protection element 10A. Figure 1 The protection circuit 1A of (a) is different. Figure 3 Other structures of protection circuit 1B of (a) are similar to Figure 1 The protection circuit 1A of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0097] The protection circuit 1B includes a protection element 10B, multiple secondary battery units 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. For example... Figure 3 As shown in (b), the protective element 10B has a second fusible conductor 17 between the heating element 16 and the fourth terminal 14. The second fusible conductor 17 can be a structure that melts due to heat generated by the heating element 16, similar to the first fusible conductor 15, or it can be connected via the first energized path P1. A The structure utilizes self-heating (Joule heating) to melt the current flowing through it. Additionally, in this modified example, the protective element 10B has a second fusible conductor 17 between the heating element 16 and the fourth terminal 14, but it is not limited to this; the second fusible conductor 17 may also be between the heating element 16 and the third terminal 13. Thus, through the first energizing path P1 of the protective element 10B... A A second fusible conductor 17 is provided, in addition to the second energized path P2. A In addition to cutting off the circuit, it can also cut off the first power path P1. A This allows for the construction of more secure protection circuits.

[0098] Figure 4 (a) means Figure 1 Circuit diagram of other variations of the protection circuit 1A of (a). Figure 4 The protection circuit 1C of (a) is similar to the protection element 10C in that it replaces the protection element 10A. Figure 1 The protection circuit 1A is different. Figure 4 Other structures of the protection circuit 1C of (a) are similar to Figure 1 The protection circuit 1A of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0099] like Figure 4As shown in (a), the protection circuit 1C includes a protection element 10C, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. Figure 4 As shown in (b), the protective element 10C has a second fusible conductor 17 between the heating element 16 and the third terminal 13 of the protective element 10B, and a third fusible conductor 18 between the heating element 16 and the fourth terminal 14. The second fusible conductor 17 can be a structure that melts due to the heat generated by the heating element 16, similar to the first fusible conductor 15, or it can be connected via the first energized path P1. A The current flowing through it is melted by self-heating (Joule heating). The third fusible conductor 18 can be melted by heat generated by the heating element 16, similar to the first fusible conductor 15, or it can be melted by heat in the current-carrying path P1. A The current flowing through it is melted by self-heating (Joule heating). Alternatively, the second fusible conductor 17 and the third fusible conductor 18 can be cut off by applying pressure to the heating element 16 using a pressing unit (not shown). Thus, the current is cut off through the energizing path P1 of the protective element 10C. A A second fusible conductor 17 and a third fusible conductor 18 are provided, except for the second energized path P2. A In addition to cutting off the circuit, it can also reliably cut off the first energized path P1. A This allows for the construction of more secure protection circuits.

[0100] Figure 5 (a) is a circuit diagram that schematically illustrates an example of the structure of the protection circuit according to the second embodiment of the present invention. Figure 5 (b) is a diagram that schematically represents an example of the structure of a protective element. Figure 5 The structure of protection circuit 1D (a) differs from that of protection circuit 1A in that the auxiliary power supply 40 is electrically connected to multiple secondary battery units 20, 20, ... Figure 5 Other structures of the protection circuit 1D of (a) and Figure 1 The protection circuit 1A of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0101] like Figure 5 As shown in (a), the protection circuit 1D includes a protection element 10A, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. The heating element 16 of the protection element 10A is disposed in the first energizing path P1 between the third terminal 13 and the fourth terminal 14. B .

[0102] In this embodiment, the positive terminal 40a of the auxiliary power supply 40 is connected to the switch 60, and the negative terminal 40b is connected to the external negative terminal 30b. The negative terminal 40b of the auxiliary power supply 40 is connected to the negative terminals 20b of multiple secondary battery cells 20, 20, ... via the first fusible conductor 15 of the protection element 10A. Furthermore, a second energizing path P2 is connected to the first terminal 11 and the second terminal 12 of the protection element 10A. B and the third energizing path P3 connecting the third terminal 13 to the fourth terminal 14 via the auxiliary power supply 40 and the switch 60. B connect.

[0103] Similar to protection circuit 1A, in protection circuit 1D, the switch 60 is also switched on according to the signal from the first control device 50, the heating element 16 of the protection element 10A heats up, the first fusible conductor 15 melts, and the connection between the multiple secondary battery cells 20, 20, ... and the external negative terminal 30b is cut off.

[0104] According to this embodiment, even in the second energized path P2 B In the event of high voltage and high current, by reducing the voltage in the first energized path P1 B The voltage applied to the heating element 16 is sufficiently high to ensure voltage resistance, resulting in reliable disconnection of the charging and discharging circuits of multiple secondary battery cells 20, 20, ... achieving high safety. Furthermore, by configuring the circuit of the protection element 10A on the GND side, the voltage between the heating element 16 and the first fusible conductor 15 can be reduced to only the voltage of the auxiliary power supply 40. For example, when the protection circuit 1D is applied to the charging and discharging circuit of an electric vehicle, by using the vehicle's battery (e.g., 48V) independently mounted with the multiple secondary battery cells 20, 20, ... for power as the auxiliary power supply 40, a protection circuit with improved safety and high versatility can be constructed. In addition, space-saving design of the protection circuit and suppression of increased vehicle weight are achieved.

[0105] Figure 6 (a) and Figure 6 (b) means Figure 5 The protection circuit 1D of (a) and Figure 5 The diagram shows a modified example of the protective element in (b). Figure 6 The protection circuit 1E of (a) is similar to the one in that it has a protection element 10B instead of protection element 10A. Figure 5 The protection circuit 1D of (a) is different.

[0106] The protection circuit 1E includes a protection element 10B, multiple secondary battery units 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. For example...Figure 6 As shown in (b), the protective element 10B has a second fusible conductor 17 between the heating element 16 and the fourth terminal 14. In this modified example, the protective element 10B has a second fusible conductor 17 between the heating element 16 and the fourth terminal 14, but it is not limited to this; the second fusible conductor 17 may also be between the heating element 16 and the third terminal 13. Thus, through the first energizing path P1 of the protective element 10B... B A second fusible conductor 17 is provided, in addition to the second energized path P2. B In addition to cutting off the circuit, it can also cut off the first power path P1. B This allows for the construction of more secure protection circuits.

[0107] Figure 7 (a) and Figure 7 (b) means Figure 5 The protection circuit 1D of (a) and Figure 5 Figure (b) shows other variations of the protective element 10A. Figure 7 The protection circuit 1F of (a) is similar to the one that replaces protection element 10A and has protection element 10C. Figure 5 The protection circuit is different from 1D.

[0108] like Figure 7 As shown in (a), the protection circuit 1F includes a protection element 10C, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. Figure 6 As shown in (b), the protection element 10C has a second fusible conductor 17 between the heating element 16 and the third terminal 13 of the protection element 10B, and a third fusible conductor 18 between the heating element 16 and the fourth terminal 14. Thus, through the energizing path P1 of the protection element 10C... B A second fusible conductor 17 and a third fusible conductor 18 are provided, except for the second energized path P2. B In addition to cutting off the circuit, it can also reliably cut off the first energized path P1. B This allows for the construction of more secure protection circuits.

[0109] Figure 8 (a) is a circuit diagram that schematically illustrates an example of the structure of the protection circuit according to the third embodiment of the present invention. Figure 8 (b) is a diagram that schematically represents an example of the structure of a protective element. Figure 8 The structure of the protection circuit 1G in (a) differs from that of the protection circuit 1D in that the third terminal 13 of the protection element 10D is connected to the second terminal 12 within the protection element 10D. Figure 8Other structures of the protection circuit 1G of (a) are similar to Figure 5 The protection circuit 1D of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0110] like Figure 8 As shown in (a), the protection circuit 1G includes a protection element 10D, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. The protection element 10D has a first terminal 11, a second terminal 12, a first fusible conductor 15 connected to the first terminal 11 and the second terminal 12 at both ends, a third terminal 13, and a first energizing path P1 disposed between the third terminal 13 and the second terminal 12. C The heating element 16. In this embodiment, the heating element 16 is disposed in the first power path P1 between the third terminal 13 and the second terminal 12. C However, it is not limited to this, and it can also be set in the first power path between the third terminal 13 and the first terminal 11.

[0111] In this embodiment, the positive terminal 40a of the auxiliary power supply 40 is connected to the switch 60, and the negative terminal 40b is connected to the external negative terminal 30b. The negative terminal 40b of the auxiliary power supply 40 is connected to the negative terminals 20b of multiple secondary battery cells 20, 20, ... via the first fusible conductor 15 of the protection element 10D. Furthermore, the third terminal 13 of the protection element 10D is connected via the auxiliary power supply 40 and the switch 60 to a second energized path P2 that connects the first terminal 11 and the second terminal 12 of the protection element 10D. C Connection. Additionally, a second energized path P2 is connected to the first terminal 11 and the second terminal 12 of the protection element 10D. C The pole of the auxiliary power supply 40 that is opposite to the pole connected to the third terminal 13 can also be connected to the same pole.

[0112] Similar to protection circuit 1D, in protection circuit 1G, the switch 60 is also switched on according to the signal from the first control device 50, the heating element 16 of the protection element 10D heats up, the first fusible conductor 15 melts, and the connection between the multiple secondary battery cells 20, 20, ... and the external negative terminal 30b is cut off.

[0113] According to this embodiment, even in the second energized path P2 C In the event of high voltage and high current, by reducing the voltage in the first energized path P1 C The voltage applied to the heating element 16 is sufficient to ensure voltage resistance, resulting in reliable disconnection of the charging and discharging circuits of multiple secondary battery cells 20, 20, ... achieving high safety. Furthermore, withFigure 5 Similarly, in protection circuit 1D of (a), by configuring the circuit of protection element 10D on the GND side, the voltage between the heating element 16 and the first fusible conductor 15 can be made only the voltage of the auxiliary power supply 40. Therefore, a protection circuit with high versatility while improving safety can be constructed. In addition, space-saving of the protection circuit and suppression of the increase in vehicle weight can be achieved. Moreover, since protection element 10D has a structure without a fourth terminal 14, the structure of protection element 10D can be simplified, thereby simplifying and reducing the weight of the protection circuit 1G.

[0114] Figure 9 (a) and Figure 9 (b) means Figure 8 The protection circuit 1G of (a) and Figure 8 The diagram shows a modified example of the protective element 10D in (b). Figure 9 The protection circuit 1H of (a) is similar to the one that replaces protection element 10D and has protection element 10E. Figure 8 The protection circuit of (a) is different from that of 1G.

[0115] The protection circuit 1H includes a protection element 10E, multiple secondary battery units 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. For example... Figure 9 As shown in (b), the protective element 10E has a second fusible conductor 17 between the heating element 16 and the third terminal 13. In this modified example, the protective element 10E has a second fusible conductor 17 between the heating element 16 and the third terminal 13 of the protective element 10B, but it is not limited to this; the second fusible conductor 17 may also be between the heating element 16 and the second terminal 12 of the protective element 10E. Thus, through the first energizing path P1 of the protective element 10E... C A second fusible conductor 17 is provided, in addition to the second energized path P2. C In addition to cutting off the circuit, it can also cut off the first power path P1. C This allows for the construction of more secure protection circuits.

[0116] Figure 10 (a) and Figure 10 (b) means Figure 8 The protection circuit 1G of (a) and Figure 8 Figure (b) shows other variations of the protective element 10D. Figure 10 The protection circuit 1J of (a) is similar to the one that replaces the protection element 10D and has the protection element 10F. Figure 8 The protection circuit is different from 1G.

[0117] like Figure 10As shown in (a), the protection circuit 1J includes a protection element 10F, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. Figure 10 As shown in (b), the protection element 10F has a second fusible conductor 17 between the heating element 16 and the third terminal 13, and a third fusible conductor 18 between the heating element 16 and the second terminal 12. Thus, through the energizing path P1 of the protection element 10F... C A second fusible conductor 17 and a third fusible conductor 18 are provided, except for the second energized path P2. C In addition to cutting off the circuit, it can also reliably cut off the first energized path P1. C This allows for the construction of more secure protection circuits.

[0118] Figure 11 This is a circuit diagram that schematically illustrates an example of the structure of the protection circuit according to the fourth embodiment of the present invention. Figure 11 The difference between the structure of the protection circuit 1K and the protection circuit 1D is that the protection element 10D is located between the external positive terminal 30a and multiple secondary battery units 20, 20, ... Figure 11 Other structures of the protection circuit 1K and Figure 8 The protection circuit 1G of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0119] like Figure 11 As shown, the protection circuit 1K includes a protection element 10D, multiple secondary battery cells 20, 20, ..., an external positive terminal 30a and an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. The protection element 10D has a first terminal 11, a second terminal 12, a first fusible conductor 15 connected at both ends to the first terminal 11 and the second terminal 12, a third terminal 13, and a first energizing path P1 disposed between the third terminal 13 and the first terminal 11. D The heating element 16. In this embodiment, the heating element 16 is disposed in the first power path P1 between the third terminal 13 and the first terminal 11. C However, it is not limited to this, and it can also be set in the first power path between the third terminal 13 and the second terminal 12.

[0120] In this embodiment, the positive terminal 40a of the auxiliary power supply 40 is connected to the external positive terminal 30a, and the negative terminal 40b is connected to the switch 60. Furthermore, the positive terminal 40a of the auxiliary power supply 40 is connected to the positive terminals 20a of the plurality of secondary battery cells 20, 20, ... via the first fusible conductor 15 of the protection element 10D. Additionally, the third terminal 13 of the protection element 10D is connected via the auxiliary power supply 40 and the switch 60 to a second energized path P2, which connects the first terminal 11 and the second terminal 12 of the protection element 10D. D Connection. Additionally, a second energized path P2 is connected to the first terminal 11 and the second terminal 12 of the protection element 10D. D The pole of the auxiliary power supply 40, which is opposite to the pole connected to the third terminal 13, can also be connected to the same pole.

[0121] Similar to protection circuit 1G, in protection circuit 1K, the switch 60 is also energized based on a signal from the first control device 50. The heating element 16 of the protection element 10D heats up, the first fusible conductor 15 melts, and the connection between the multiple secondary battery cells 20, 20, ... and the external positive terminal 30a is severed. Therefore, even in the second energizing path P2... D In the event of high voltage and high current, by reducing the voltage in the first energized path P1 D The voltage applied to the heating element 16 is also sufficient to ensure voltage resistance, thus achieving high safety.

[0122] Figure 12 It means Figure 8 Figure (a) shows other variations of the protection circuit 1G. Figure 12 The structure of the protection circuit 1L and Figure 8 The protection circuit 1G of (a) has a basically the same structure. The same structural elements are marked with the same symbols and their descriptions are omitted. The following mainly describes the different parts.

[0123] like Figure 12 As shown, the first control device 50 can also receive signals from control devices 91 such as the ECU mounted in the vehicle, and output signals to the switch 60 based on these signals. For example, the control device 91 outputs signals to the switch 60 when it detects any one or both of the abnormal voltages of the multiple secondary battery cells 20, 20, ... and other abnormalities occurring in the vehicle. According to this modification, not only are abnormal voltages of the multiple secondary battery cells 20, 20, ... detected, but various abnormalities occurring in the vehicle are also detected, and the multiple secondary battery cells 20, 20, ... are disconnected from the external negative terminal 30b. Therefore, by cooperating with the control device 91 in the vehicle, higher safety can be achieved.

[0124] The above describes embodiments of the present application, but the present application is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the present application described in the claimed scope.

[0125] Industrial applicability

[0126] The protection circuit of the present application can be applied to a charge / discharge circuit of various secondary batteries such as lithium ion batteries. It is particularly suitable for a charge / discharge circuit of a mobile body using a secondary battery as a power source, such as a vehicle, a ship, an airplane, and the like.

[0127] Explanation of symbols

[0128] 1A protection circuit

[0129] 1B protection circuit

[0130] 1C protection circuit

[0131] 1D protection circuit

[0132] 1E protection circuit

[0133] 1F protection circuit

[0134] 1G protection circuit

[0135] 1H protection circuit

[0136] 1J protection circuit

[0137] 1K protection circuit

[0138] 1L protection circuit

[0139] 2 fuse element

[0140] 2a one end

[0141] 2b the other end

[0142] 2c cutting portion

[0143] 3a heat generating body

[0144] 3b male member

[0145] 3c protrusion

[0146] 3 movable member

[0147] 4 female member

[0148] 4a recess

[0149] 5 pressing unit

[0150] 6 housing

[0151] 6a first terminal

[0152] 6b second terminal

[0153] 10 protective element

[0154] 10A protective element

[0155] 10B protective element

[0156] 10C protective element

[0157] 10D protective element

[0158] 10E protective element

[0159] 10F protective element

[0160] 11 first terminal

[0161] 12 second terminal

[0162] 13 third terminal

[0163] 14 fourth terminal

[0164] 15 first fusible conductor

[0165] 15a one end

[0166] 15b multiple ends

[0167] 16 heat generating body

[0168] 17 second fusible conductor

[0169] 18 third fusible conductor

[0170] 20 secondary battery cell

[0171] 20a positive electrode terminal

[0172] 20b negative electrode terminal

[0173] 30a external positive electrode terminal

[0174] 30b external negative electrode terminal

[0175] 40 auxiliary power supply

[0176] 40a positive electrode terminal

[0177] 40b negative electrode terminal

[0178] 50 first control device

[0179] 60 switch

[0180] 80 second control device

[0181] 90 switch

[0182] 91 control device

Claims

1. A protection circuit, characterized in that, have: A protective element having a first terminal, a second terminal, a first fusible conductor with its two ends connected to the first terminal and the second terminal, a third terminal, a fourth terminal, and a heating element disposed on a first energizing path between the third terminal and the fourth terminal; Multiple secondary battery cells connected in series; External positive end and external negative end; Auxiliary power supply; A control device that monitors the voltage of the plurality of secondary battery cells, detects abnormalities, and outputs signals; as well as A switch that receives a signal from the control device to switch the power supply on and off. The control device is connected to the plurality of secondary battery units. The first terminal and the second terminal of the protection element are disposed in a second power path between the positive terminal of the plurality of secondary battery cells and the external positive terminal or between the negative terminal of the plurality of secondary battery cells and the external negative terminal. The third and fourth terminals of the protection element are connected in series with the auxiliary power supply and the switch, forming a loop. The second energizing path, which connects the first terminal and the second terminal of the protection element, is connected to the third energizing path, which connects from the third terminal via the auxiliary power supply and the switch to the fourth terminal. The switch is switched on according to the signal from the control device, the heating element of the protection element heats up, the first fusible conductor melts, and the connection between the plurality of secondary battery units and the external positive terminal or between the plurality of secondary battery units and the external negative terminal is cut off.

2. The protection circuit according to claim 1, characterized in that, A second fusible conductor is provided between the heating element of the protective element and the third terminal or between the heating element of the protective element and the fourth terminal.

3. The protection circuit according to claim 1, characterized in that, A second fusible conductor is provided between the heating element and the third terminal of the protective element, and a third fusible conductor is provided between the heating element and the fourth terminal.

4. A protection circuit, characterized in that, have: A protective element having a first terminal, a second terminal, a first fusible conductor with its two ends connected to the first terminal and the second terminal, a third terminal, and a heating element disposed on a first energizing path between the third terminal and the first terminal or the second terminal; Multiple secondary battery cells connected in series; External positive end and external negative end; Auxiliary power supply; A control device that monitors the voltage of the plurality of secondary battery cells, detects abnormalities, and outputs signals; as well as A switch that receives a signal from the control device to switch the power supply on and off. The control device is connected to the plurality of secondary battery units. The first and second terminals of the protection element are disposed in a second power path between the positive terminals of the plurality of secondary battery cells and the external positive terminal, or between the negative terminals of the plurality of secondary battery cells and the external negative terminal. The third terminal of the protection element is connected to the second energized path, which connects the first and second terminals of the protection element, via the auxiliary power supply and the switch. The switch is switched on according to the signal from the control device, the heating element of the protection element heats up, the first fusible conductor melts, and the connection between the plurality of secondary battery units and the external positive terminal or between the plurality of secondary battery units and the external negative terminal is cut off.

5. The protection circuit according to claim 4, characterized in that, A second fusible conductor is provided between the heating element and the third terminal of the protective element.

6. The protection circuit according to claim 4, characterized in that, The protective element has a second fusible conductor between the heating element and the third terminal, and a third fusible conductor between the heating element and the first terminal or the second terminal.

7. The protection circuit according to any one of claims 1 to 6, characterized in that, The pole of the second energized path of the first and second terminals of the protection element is connected to the opposite pole of the auxiliary power supply connected to the third terminal in a manner that they are of the same polarity.

8. The protection circuit according to any one of claims 1 to 6, characterized in that, The first fusible conductor is a laminate comprising a low-melting-point metal layer and a high-melting-point metal layer.

9. The protection circuit according to claim 8, characterized in that, The low-melting-point metal layer is composed of Sn or an alloy with Sn as the main component, and the high-melting-point metal layer is composed of Ag or Cu, or an alloy with Ag or Cu as the main component.

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