Protection circuit

Abstract

To provide a protection circuit capable of improving high safety.SOLUTION: A protection circuit 1D includes a protection element 10A, a plurality of secondary battery cells 20, an external positive terminal 30a, an external negative terminal 30b, an auxiliary power supply 40, a first control device 50, and a switch 60. The protection element 10A has a first fusible conductor 15, of which both ends are connected to the first terminal 11 and the second terminal 12, and a heating element 16 installed on a first current path P1B between a third terminal 13 and fourth terminal 14. A second current path P2B to which the first terminal 11 and the second terminal 12 are connected, and a third current path P3B linking from the third terminal 13 to the fourth terminal 14 via the auxiliary power supply 40 and the switch 60 are connected. The switch 60 is switched to energize by a signal from the first control device 50, the heating element 16 of the protection element 10A generates heat, and the first fusible conductor 15 melts to block between the plurality of secondary battery cells 20 and the external negative terminal 30b.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a protection circuit, for example, a protection circuit provided in a charge and discharge circuit of a secondary battery.

Background Art

[0002] Lithium-ion batteries are widely used as power sources for mobile devices such as notebook computers. A protection circuit for a secondary battery such as a lithium-ion battery is equipped with a fuse with a surface-mounted heater (Self Control Protector, hereinafter also referred to as SCP). When an overvoltage abnormality occurs, power is supplied from the secondary battery itself to the heater to generate heat and melt the fuse element.

[0003] For example, as a conventional protection circuit, as shown in FIGS. 13(a) and 13(b), fuse elements 111, 111 connected in an energization path, and a heater 112 connected to the fuse elements 111, 111 and capable of melting the fuse elements 111, 111 by heating, an SCP110 having the same, an IC130 for detecting abnormalities in battery cells 121, 121,... of a battery 120 connected to the above energization path, and based on the detection result of the IC130, a FET140 that operates to supply power to the heater 112 of the SCP110, an IC150 for detecting an abnormality in the entire battery 120, and based on the detection result of the IC150, there is a protection circuit 100 including FETs 160, 160 that operate to supply power to the heater 112 of the SCP110. In this protection circuit 100, when an abnormality in each battery cell is detected, the FET140 is turned on, power is supplied from the battery 120 to the heater 112 of the SCP110 to generate heat, and the fuse element 111 is melted.

[0004] Also, as another conventional protection circuit, a protection circuit has been proposed in which a fusible conductor (fuse element) is disposed between a data server and an Internet line, and includes a heating element provided independently of the above fusible conductor and an external power source dedicated to the heating element (Patent Document 1).

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when a conventional protection circuit as shown in Fig. 13(a) is mounted on a charge / discharge circuit of a large-capacity secondary battery for power applications, there is a problem that the heater is destroyed by a significantly high voltage and large current. These days, lithium-ion batteries as secondary batteries have been evolving from mobile device applications to applications such as EVs and storage batteries, and their capacity is increasing. In addition, with the increase in the capacity of lithium-ion batteries, the voltage is a high-voltage specification of several hundred volts and the current is also a large-current specification of several hundred amperes, and a highly safe protection circuit that can meet these needs is required.

[0007] In the protection circuit of Patent Document 1, regardless of the type of an external circuit such as a data server, it is possible to supply power sufficient to generate a heat amount sufficient to melt a fusible conductor with respect to a heating element, and it is said that it can be applied to a digital signal circuit that passes a weak current as an external circuit. That is, in Patent Document 1, a configuration for applying a protection circuit to a signal circuit to prevent information leakage due to hacking or the like is disclosed to such an extent, and there is no disclosure or suggestion of applying the protection circuit to a charge / discharge circuit of a secondary battery for power applications. Also, if the circuit voltage is a low-voltage specification of several tens of volts, it may be considered that the above protection circuit can be applied, but in the case of high-voltage and large-current specifications such as several hundred volts and several hundred amperes, it is difficult to ensure the withstand voltage of the heating element and the insulation after the fusible conductor is cut off, so it is difficult to apply the above protection circuit to a charge / discharge circuit of a large-capacity secondary battery.

[0008] An object of the present invention is to provide a protection circuit that can surely cut off a charge / discharge circuit of a secondary battery and achieve high safety.

Means for Solving the Problems

[0009] To achieve the above object, the present invention provides the following means.

[0010] [1] A protection element having a first terminal, a second terminal, a first soluble conductor having both ends connected to the first terminal and the second terminal, a third terminal, a fourth terminal, and a heating element installed in a first current path between the third terminal and the fourth terminal; A plurality of secondary battery cells connected in series; An external positive terminal and an external negative terminal; An auxiliary power source provided electrically independently of the plurality of secondary battery cells; A control device that monitors the voltage of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; A switch that receives the signal of the control device and switches the energization, The control device is connected to the plurality of secondary battery cells, The first terminal and the second terminal of the protection element are installed in a second current path between the positive electrode terminal of the plurality of secondary battery cells and the external positive terminal or between the negative electrode terminal of the plurality of secondary battery cells and the external negative terminal, The third terminal and the fourth terminal of the protection element are connected in series and loop-shaped with the auxiliary power source and the switch, The switch is switched to be energized by the signal from the control device, the heating element of the protection element generates heat, and the first soluble conductor is melted to cut off between the plurality of secondary battery cells and the external positive terminal or between the plurality of secondary battery cells and the external negative terminal. A protection circuit.

[0011] [2] The protection circuit according to [1] above, having a second soluble conductor between the heating element of the protection element and the third terminal or between the heating element of the protection element and the fourth terminal.

[0012] [3] The protection circuit according to [1] above, having a second soluble conductor between the heating element of the protection element and the third terminal, and having a third soluble conductor between the heating element and the fourth terminal.

[0013] [4] A protection element having a first terminal, a second terminal, a first soluble conductor with both ends connected to the first terminal and the second terminal, a third terminal, a fourth terminal, and a heating element installed in a first current path between the third terminal and the fourth terminal; A plurality of secondary battery cells connected in series; An external positive terminal and an external negative terminal; An auxiliary power source; A control device that monitors the voltage of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; A switch that receives the signal from the control device and switches the energization, The control device is connected to the plurality of secondary battery cells, The first terminal and the second terminal of the protection element are installed in a second current path between the positive electrode end of the plurality of secondary battery cells and the external positive terminal or between the negative electrode end of the plurality of secondary battery cells and the external negative terminal; The third terminal and the fourth terminal of the protection element are connected in series and loop-like with the auxiliary power source and the switch, The second current path in which the first terminal and the second terminal of the protection element are connected, and the third current path that connects from the third terminal to the fourth terminal through the auxiliary power source and the switch are connected; The switch is switched to be energized by the signal from the control device, the heating element of the protection element generates heat, and the first soluble conductor is melted to cut off between the plurality of secondary battery cells and the external positive terminal or between the plurality of secondary battery cells and the external negative terminal.

[0014] [5] The protection circuit according to [4] above, having a second soluble conductor between the heating element of the protection element and the third terminal or between the heating element of the protection element and the fourth terminal.

[0015] [6] The protection circuit according to [4] above, having a second soluble conductor between the heating element of the protection element and the third terminal, and having a third soluble conductor between the heating element and the fourth terminal.

[0016] [7] A protection element having a first terminal, a second terminal, a first soluble conductor having both ends connected to the first terminal and the second terminal, a third terminal, and a heating element installed in a first current path between the third terminal and the first terminal or the second terminal; A plurality of secondary battery cells connected in series; An external positive terminal and an external negative terminal; An auxiliary power source; A control device that monitors the voltage of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; A switch that receives the signal from the control device and switches the energization, The control device is connected to the plurality of secondary battery cells, The first terminal and the second terminal of the protection element are installed in a second current path between the positive electrode end of the plurality of secondary battery cells and the external positive terminal or between the negative electrode end of the plurality of secondary battery cells and the external negative terminal, The third terminal of the protection element is connected to the second current path to which the first terminal and the second terminal of the protection element are connected via the auxiliary power source and the switch, and the switch is switched to be energized by the signal from the control device, and the heating element of the protection element generates heat and the first soluble conductor is melted to cut off between the plurality of secondary battery cells and the external positive terminal or between the plurality of secondary battery cells and the external negative terminal.

[0017] [8] The protection circuit according to [7] above, having a second soluble conductor between the heating element of the protection element and the third terminal.

[0018] [9] The protection circuit according to [7] above, having a second soluble conductor between the heating element of the protection element and the third terminal, and having a third soluble conductor between the heating element and the first terminal or the second terminal.

[0019]

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

[0020]

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

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

[0021]

[12] The protection circuit according to

[11] above, wherein the low melting point metal layer is composed of Sn or an alloy mainly containing Sn, and the high melting point metal layer is composed of Ag or Cu, or an alloy mainly containing Ag or Cu.

Advantages of the Invention

[0022] According to the present invention, the charge and discharge circuit of the secondary battery can be surely interrupted, and high safety can be realized.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

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Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The drawings used in the following description may show the characteristic parts enlarged for convenience of understanding the characteristics, and the dimensional ratios of the respective components may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and it can be appropriately modified and implemented within the scope in which the effects of the present invention can be achieved.

[0025] FIG. 1(a) is a circuit diagram schematically showing an example of the configuration of a protection circuit according to the first embodiment of the present invention. As shown in FIG. 1(a), the protection circuit 1A includes a protection element 10A, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a and an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50 (control device), and a switch 60. The plurality of secondary battery cells 20, 20, ··· are connected in series, and the positive electrode ends 20a of the plurality of secondary battery cells 20, 20, ··· are connected to the external positive electrode terminal described later, and the negative electrode ends 20b are connected to the external non-negative electrode terminal described later. The plurality of secondary battery cells 20, 20, ··· are secondary batteries, and examples include lithium ion secondary batteries. The total voltage of the plurality of secondary battery cells 20, 20, ··· is at least 100V or more in the case of a storage battery application, and for example, 350V or more and 800V or less in the case of an EV application. The protection circuit 1A has an external positive electrode terminal 30a and an external negative electrode terminal 30b, and is connected to an external charging device via these external positive electrode terminal 30a and external negative electrode terminal 30b.

[0026] As shown in FIG. 1(b), the protection element 10A includes a first terminal 11, a second terminal 12, a first fusible conductor 15 having both ends connected to the first terminal 11 and the second terminal 12, a third terminal 13, a fourth terminal 14, and a first current path P1 between the third terminal 13 and the fourth terminal 14 A in which a heating element 16 is provided. In the present embodiment, the first terminal 11 and the second terminal 12 of the protection element 10A are provided in a second current path P2 between the negative electrode ends 20b of the plurality of secondary battery cells 20, 20, ··· and the external negative electrode terminal 30b. A Also, the third terminal 13 and the fourth terminal 14 of the protection element 10A are connected in series and loop-shaped with the auxiliary power source 40 and the switch 60.

[0027] The first fusible conductor 15 is composed of, for example, a fuse element housed in a housing (not shown). The fuse element is, for example, in the form of a thin sheet or a rod. 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.

[0028] The first soluble conductor 15 is preferably a laminate including a low melting point metal layer and a high melting point metal layer made of a high melting point metal having a melting point higher than that of the low melting point metal. Further, the first soluble conductor 15 more preferably has a coating 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 soluble conductor 15 may be a laminate having a three-layer structure in which an inner layer and an outer layer sandwiching the inner layer are laminated in the thickness direction, and the inner layer and the outer layer are made of materials having different softening temperatures. In such a first soluble conductor 15, among the inner layer and the outer layer of the laminate, the mixed state of the solid phase and the liquid phase starts earlier in the layer of the material having a lower softening temperature, and the layer of the material having a higher softening temperature can be cut before reaching the softening temperature.

[0029] The low melting point metal layer is made of, for example, Sn or an alloy mainly composed of Sn. Since the melting point of Sn is 232°C, the metal mainly composed of Sn has a low melting point and becomes soft at a low temperature. For example, the solidus line of the Sn / Ag3% / Cu0.5% alloy is 217°C. Further, as the material constituting the low melting point metal layer, various low melting point metals conventionally used as fuse materials can be used. Examples of the low melting point metal include 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.

[0030] The material constituting the high melting point metal layer is made of, for example, Ag or Cu, or an alloy mainly composed of Ag or Cu. Since the melting point of Ag is 962°C and the melting point of copper is 1085°C, the layer made of a metal mainly composed of Ag or Cu maintains its rigidity at the temperature at which the layer made of the low melting point metal becomes soft.

[0031] The heating element 16 is a plate-shaped member and has, for example, an insulating substrate and a heating portion formed on the insulating substrate. The heating element 16 is arranged in contact with the first soluble conductor 15 or arranged directly above the first soluble conductor 15. In this case, the heating element 16 preferably has a function of heating and softening the first soluble conductor 15 and a function of applying the pressing force of the pressing means described later to the first soluble conductor 15 to cut the first soluble conductor 15.

[0032] As the insulating substrate, a known substrate having insulating properties can be used, and examples thereof include those made of alumina, glass ceramics, mullite, zirconia, and the like.

[0033] The heating portion is preferably a resistor made of a conductive material that generates heat when energized. Examples of the material of the heating portion include materials containing metals such as nichrome, W, Mo, and Ru. This heating portion is formed, for example, by applying a resistive paste composed of a conductive material such as ruthenium oxide or carbon black and an inorganic binder such as water glass or an organic binder such as a thermosetting resin, and firing as necessary. Further, as the heating portion, a thin film such as ruthenium oxide or carbon black may be formed through processes such as printing, plating, vapor deposition, and sputtering, or may be formed by pasting or laminating these films.

[0034] FIG. 2(a) and FIG. 2(b) are cross-sectional views showing a structural example of the protection element 10A in FIG. 1(b). The structure of the protection element 10A in FIG. 2(a) and FIG. 2(b) is an example, and the structure of the protection element of the present invention is not limited thereto. As shown in FIG. 2(a), the protection element 10A includes a fuse element (first soluble conductor) 2 having a cut 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 means 5, and a case 6.

[0035] One end 2a of the fuse element 2 is connected to the first terminal 6a, and the other end 2b is connected to the second terminal 6b, respectively, by soldering 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 a function of applying the pressing force of the pressing means 5 to the cutting portion 2c of the fuse element 2, and the convex portion 3c of the convex member 3b is in pressure contact with the heating element 3a. The concave member 4 is disposed opposite to the movable member 3 and sandwiches the cutting portion 2a of the fuse element 2 in cooperation with the movable member 3. The concave portion 4a of the concave member 4 is formed so as to be able to accommodate the convex portion 3c of the heating element 3a. The pressing means 5 applies a force to the movable member 3 so that the movable member 3 and the concave member 4 sandwich the cutting portion 2c and reduce their relative distance when the cutting portion 2a is cut. As the pressing means 5, for example, a spring is used and is accommodated between the convex member 3b and the case 6 while maintaining a restoring force in the Z direction.

[0036] In this protection element 10A, when the heating element 3a of the movable member 3 generates heat, the fuse element 2 softens at a temperature equal to or higher than the softening temperature of the fuse element 2. Along with this, the convex portion 3c of the convex member 3b enters the concave portion 4a of the concave member 4 due to the pressing force of the pressing means 5. As a result, the cutting portion 2c is separated from one end 2a (or the other end 2b), and the fuse element 2 is cut (FIG. 2(b)).

[0037] The auxiliary power source 40 is provided electrically independently of the plurality of secondary battery cells 20, 20, ···. The auxiliary power source 40 is not particularly limited as long as it can supply power capable of melting the first fusible conductor 15 when energized. For example, it is composed of a known primary battery, a secondary battery, or the like. Examples of the secondary battery include a lead storage battery and a lithium ion battery. The voltage of the auxiliary power source is, for example, 10V or more and 56V or less.

[0038] The first control device 50 is connected to a 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, and is connected to the second energization path P2 of the protection element 10A A to detect the voltage of each of the plurality of secondary battery cells 20, 20, ··· connected thereto, and determines whether an abnormality such as overcharging has occurred in the plurality of secondary battery cells 20, 20, ··· based on the voltage. When an abnormality occurs in the plurality of secondary battery cells 20, 20, ···, the first control device 50 shuts off the energization path by operating the protection element 10A.

[0039] The switch 60 receives the signal from the first control device 50 and switches the energization. The switch 60 is not particularly limited, and is, for example, a field effect transistor (hereinafter also referred to as FET). As the FET, there is no particular limitation, and for example, a junction FET or a MOS FET 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 heating element 16. The switch 60 operates in an on or off manner according to a control signal output from the first control device 50.

[0040] 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 overall voltage of the plurality of secondary battery cells 20, 20, ···, detects an abnormality, and outputs a signal. The switches 90, 90 receive the signal from the second control device 80 and switch the energization. The switches 90, 90 are not particularly limited, and are, for example, FETs. It is preferable that the protection circuit 1A includes the second control device 80 and the switches 90, 90, but it may not include them.

[0041] In the protection circuit 1A configured as described above, during charging of the plurality of secondary battery cells 20, 20, ···, power is supplied from the charging device to the plurality of secondary battery cells 20, 20, ··· via an external circuit. Also, during discharging of the plurality of secondary battery cells 20, 20, ···, power is supplied from the plurality of secondary battery cells 20, 20, ··· to the external circuit. A load such as a motor or a converter (not shown) is connected to the external circuit.

[0042] In this protection circuit 1A, the switch 60 is switched to be energized by a signal from the first control device 50, the heating element 16 of the protection element 10 generates heat, and the first fusible conductor 15 is melted to cut off the connection between the plurality of secondary battery cells 20, 20, ··· and the external negative terminal 30b. Specifically, the first control device 50 detects the voltage of each of the plurality of secondary battery cells 20, 20, ···, and when it determines that any one or a plurality of the voltages of the plurality of secondary battery cells 20, 20, ··· deviate from a predetermined value indicating an over-discharge or over-charge state, it outputs a control signal to the switch 60. And the first energization path P1 A When the upper switch 60 is turned on, power is supplied from the auxiliary power source 40 to the heating element 16, and the heating element 16 generates heat. Due to the heat of this heating element 16, the second energization path P2 A The upper first fusible conductor 15 is melted, whereby the energization path of the protection circuit 1A is cut off.

[0043] As described above, according to the present embodiment, the second energization path P2 to which the plurality of secondary battery cells 20, 20, ··· connected via the first fusible conductor 15 are connected A And the first energization path P1 connecting the heating element 16 and the auxiliary power source 40 A By making the configuration independent, the specification of the heating element 16 can be appropriately selected in the first energization path P1 A Therefore, even when a large voltage and a large current occur in the second energization path P2 A The first energization path P1 ABy reducing the voltage applied to the heating element 16, a sufficient withstand voltage can be ensured. As a result, it is possible to reliably cut off the charge / discharge circuits of a plurality of secondary battery cells 20, 20, ···, and achieve high safety. In particular, even when an unexpected accident, natural disaster, or the like occurs during the use of a vehicle such as an electric vehicle, it is possible to prevent electric shock due to the charge / discharge circuits of the plurality of secondary battery cells 20, 20, ···.

[0044] Also, the first terminal 11 and the second terminal 12 of the protection element 10A are in the second current path P2 between the negative electrode terminals 20b of the plurality of secondary battery cells 20, 20, ··· and the external negative electrode terminal 30b. A They are installed therein, and since the third terminal 13 and the fourth terminal 14 of the protection element 10A are connected in series and loop-shaped with the auxiliary power source 40 and the switch 60, only the voltage of the auxiliary power source 40 can be surely applied to the heating element 16. For this reason, in a charge / discharge circuit for power such as an electric vehicle equipped with a large-capacity lithium-ion battery of several hundred volts (for example, 350V or more), a highly safe protection circuit can be constructed.

[0045] Fig. 3(a) is a circuit diagram showing a modified example of the protection circuit 1A in Fig. 1(a). The protection circuit 1B in Fig. 3(a) is different from the protection circuit 1A in Fig. 1(a) in that it has a protection element 10B instead of the protection element 10A. The other configurations of the protection circuit 1B in Fig. 3(a) are basically the same as those of the protection circuit 1A in Fig. 1(a). The same components are denoted by the same reference numerals and their descriptions are omitted, and mainly the different parts will be described below.

[0046] The protection circuit 1B includes a protection element 10B, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a and an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in Fig. 3(b), the protection element 10B has a second fusible conductor 17 between the heating element 16 of the protection element 10B and the fourth terminal 14. The second fusible conductor 17 may be configured to be melted by the heat generated by the heating element 16 in the same manner as the first fusible conductor 15, or the first current path P1. AIt may be configured to be blown by self-heating (Joule heat) due to the current flowing therethrough. Also, in this modification, the protection element 10B has the second fusible conductor 17 between the heating element 16 of the protection element 10B and the fourth terminal 14, but is not limited thereto, and may have the second fusible conductor 17 between the heating element 16 of the protection element 10B and the third terminal 13. By providing the second fusible conductor 17 in the first current path P1 of the protection element 10B as described above A in addition to cutting off the second current path P2 A it is possible to cut off the first current path P1 A and construct a more secure protection circuit.

[0047] Fig. 4(a) is a circuit diagram showing another modification of the protection circuit 1A in Fig. 1(a). The protection circuit 1C in Fig. 4(a) is different from the protection circuit 1A in Fig. 1 in that it has a protection element 10C instead of the protection element 10A. Other configurations of the protection circuit 1C in Fig. 4(a) are basically the same as those of the protection circuit 1A in Fig. 1(a). The same components are labeled with the same numbers and their descriptions are omitted, and mainly the different parts will be described below.

[0048] As shown in Fig. 4(a), the protection circuit 1C includes a protection element 10C, a plurality of secondary battery cells 20, 20, ···, an external positive terminal 30a, an external negative terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in Fig. 4(b), the protection element 10C has the second fusible conductor 17 between the heating element 16 of the protection element 10B and the third terminal 13, and has the third fusible conductor 18 between the heating element 16 and the fourth terminal 14. The second fusible conductor 17 may be configured to be blown by the heat generated in the heating element 16 in the same manner as the first fusible conductor 15, or may be configured to be blown by self-heating (Joule heat) due to the current flowing through the first current path P1 A Similarly, the third fusible conductor 18 may be configured to be blown by the heat generated in the heating element 16, or may be blown by the current flowing through the current path P1 AIt may also be configured to be melted by self-heating (Joule heat) due to the current flowing through it. Further, a pressing force of a pressing means (not shown) may be applied to the heating element 16 to cut the second fusible conductor 17 and the third fusible conductor 18. Thus, by providing the second fusible conductor 17 and the third fusible conductor 18 in the energization path P1 of the protection element 10C A in addition to cutting the second energization path P2 A the first energization path P1 A can be surely cut off, and a more secure protection circuit can be constructed.

[0049] FIG. 5(a) is a circuit diagram schematically showing an example of the configuration of a protection circuit according to the second embodiment of the present invention, and FIG. 5(b) is a diagram schematically showing an example of the configuration of a protection element. The configuration of the protection circuit 1D in FIG. 5(a) is different from the configuration of the protection circuit 1A in that the auxiliary power source 40 is electrically connected to a plurality of secondary battery cells 20, 20,.... Other configurations of the protection circuit 1D in FIG. 5(a) are basically the same as the configuration of the protection circuit 1A in FIG. 1(a). The same components are denoted by the same reference numerals and their descriptions are omitted, and mainly the different parts will be described below.

[0050] As shown in FIG. 5(a), the protection circuit 1D includes a protection element 10A, a plurality of secondary battery cells 20, 20, ···, an external positive terminal 30a, an external negative terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. The heating element 16 of the protection element 10A is installed in the first energization path P1 B between the third terminal 13 and the fourth terminal 14.

[0051] In the present embodiment, the positive terminal 40a of the auxiliary power source 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 source 40 is connected to the negative terminals 20b of the plurality of secondary battery cells 20, 20, ··· through the first fusible conductor 15 of the protection element 10A. Then, the second energization path P2 B formed by connecting the first terminal 11 and the second terminal 12 of the protection element 10A, and the third energization path P3 connecting from the third terminal 13 to the fourth terminal 14 through the auxiliary power source 40 and the switch 60B is connected.

[0052] Also in this protection circuit 1D, similar to the protection circuit 1A, the switch 60 is switched to be energized by a signal from the first control device 50, the heating element 16 of the protection element 10A generates heat, and the first fusible conductor 15 is melted to cut off the connection between the plurality of secondary battery cells 20, 20,... and the external negative terminal 30b.

[0053] According to the present embodiment, even when a large voltage and a large current occur in the second current path P2 B the withstand voltage can be sufficiently ensured by reducing the voltage applied to the heating element 16 in the first current path P1 B As a result, the charge and discharge circuits of the plurality of secondary battery cells 20, 20,... can be surely cut off, and high safety can be realized. Further, by arranging 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 made only the voltage of the auxiliary power source 40. For example, when the protection circuit 1D is applied to the charge and discharge circuit of an electric vehicle, by using a battery (for example, 48V) mounted on the vehicle separately from the plurality of secondary battery cells 20, 20,... for power as the auxiliary power source 40, a highly versatile protection circuit can be constructed while improving safety. In addition, the space occupied by the protection circuit can be reduced and an increase in the weight of the vehicle can be suppressed.

[0054] FIG. 6(a) and FIG. 6(b) are diagrams showing modified examples of the protection circuit 1D in FIG. 5(a) and the protection element in FIG. 5(b). The protection circuit 1E in FIG. 6(a) is different from the protection circuit 1D in FIG. 5(a) in that it has a protection element 10B instead of the protection element 10A.

[0055] The protection circuit 1E includes a protection element 10B, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a, an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in FIG. 6(b), the protection element 10B has a second fusible conductor 17 between the heating element 16 of the protection element 10B and the fourth terminal 14. In this modified example, the protection element 10B has the second fusible conductor 17 between the heating element 16 of the protection element 10B and the fourth terminal 14, but it is not limited to this, and the protection element 10B may have the second fusible conductor 17 between the heating element 16 and the third terminal 13. By providing the second fusible conductor 17 in the first current path P1 B of the protection element 10B, in addition to the interruption of the second current path P2 B , the first current path P1 B can be interrupted, and a more secure protection circuit can be constructed.

[0056] FIGS. 7(a) and 7(b) are diagrams showing other modified examples of the protection circuit 1D in FIG. 5(a) and the protection element 10A in FIG. 5(b). The protection circuit 1F in FIG. 7(a) is different from the protection circuit 1D in FIG. 5 in that it has a protection element 10C instead of the protection element 10A.

[0057] As shown in FIG. 7(a), the protection circuit 1F includes a protection element 10C, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a, an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in FIG. 6(b), the protection element 10C has a second fusible conductor 17 between the heating element 16 of the protection element 10B and the third terminal 13, and a third fusible conductor 18 between the heating element 16 and the fourth terminal 14. By providing the second fusible conductor 17 and the third fusible conductor 18 in the current path P1 B of the protection element 10C, in addition to the interruption of the second current path P2 B , the first current path P1 B can be surely interrupted, and a more secure protection circuit can be constructed.

[0058] FIG. 8(a) is a circuit diagram schematically showing an example of the configuration of the protection circuit according to the third embodiment of the present invention, and FIG. 8(b) is a diagram schematically showing an example of the configuration of the protection element. The configuration of the protection circuit 1G in FIG. 8(a) is different 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. The other configurations of the protection circuit 1G in FIG. 8(a) are basically the same as those of the protection circuit 1D in FIG. 5(a). The same components are denoted by the same reference numerals and their descriptions are omitted. The main differences will be described below.

[0059] As shown in FIG. 8(a), the protection circuit 1G includes a protection element 10D, a plurality of secondary battery cells 20, 20, ···, an external positive terminal 30a, an external negative terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. The protection element 10D includes a first terminal 11, a second terminal 12, a first fusible conductor 15 having both ends connected to the first terminal 11 and the second terminal 12, a third terminal 13, and a first current path P1 between the third terminal 13 and the second terminal 12. C In this embodiment, the heating element 16 is provided in the first current path P1 between the third terminal 13 and the second terminal 12. C However, the present invention is not limited to this, and it may be provided in the first current path between the third terminal 13 and the first terminal 11.

[0060] In this embodiment, the positive terminal 40a of the auxiliary power source 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 source 40 is connected to the negative terminals 20b of the plurality of secondary battery cells 20, 20, ··· through the first fusible conductor 15 of the protection element 10D. The third terminal 13 of the protection element 10D is connected to the second current path P2 where the first terminal 11 and the second terminal 12 of the protection element 10D are connected via the auxiliary power source 40 and the switch 60. C Moreover, the poles of the second current path P2 where the first terminal 11 and the second terminal 12 of the protection element 10D are connected and the poles on the side connected to the third terminal 13 of the auxiliary power source 40 may be connected with the same poles. C

[0061] Also in this protection circuit 1G, similar to the protection circuit 1D, the switch 60 is switched to be energized by a signal from the first control device 50, the heating element 16 of the protection element 10D generates heat, and the first fusible conductor 15 is melted to cut off the connection between the plurality of secondary battery cells 20, 20,... and the external negative terminal 30b.

[0062] According to this embodiment, even when a large voltage and a large current occur in the second current path P2 C the withstand voltage can be sufficiently ensured by reducing the voltage applied to the heating element 16 in the first current path P1 C As a result, the charge and discharge circuits of the plurality of secondary battery cells 20, 20,... can be surely cut off, and high safety can be realized. Also, similar to the protection circuit 1D in FIG. 5(a), by arranging the circuit of the 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 source 40. Therefore, a highly versatile protection circuit can be constructed while improving safety, and in addition, the space occupied by the protection circuit can be reduced and an increase in the weight of the vehicle can be suppressed. Furthermore, since the protection element 10D does not have the fourth terminal 14, the configuration of the protection element 10D can be simplified, and as a result, the configuration of the protection circuit 1G can be simplified and the weight can be reduced.

[0063] FIGS. 9(a) and 9(b) are diagrams showing modified examples of the protection circuit 1G in FIG. 8(a) and the protection element 10D in FIG. 8(b). The protection circuit 1H in FIG. 9(a) is different from the protection circuit 1G in FIG. 8(a) in that it has a protection element 10E instead of the protection element 10D.

[0064] The protection circuit 1H includes a protection element 10E, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a, an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in FIG. 9(b), the protection element 10E has a second fusible conductor 17 between the heating element 16 of the protection element 10E and the third terminal 13. In this modification, the protection element 10E has the second fusible conductor 17 between the heating element 16 of the protection element 10B and the third terminal 13, but is not limited thereto, and the protection element 10E may have the second fusible conductor 17 between the heating element 16 and the second terminal 12. By providing the second fusible conductor 17 in the first current path P1 of the protection element 10E C in addition to cutting off the second current path P2 C it is possible to cut off the first current path P1 C and construct a more secure protection circuit.

[0065] FIGS. 10(a) and 10(b) are diagrams showing other modifications of the protection circuit 1G of FIG. 8(a) and the protection element 10D of FIG. 8(b). The protection circuit 1J in FIG. 10(a) is different from the protection circuit 1G in FIG. 8 in that it has a protection element 10F instead of the protection element 10D.

[0066] As shown in FIG. 10(a), the protection circuit 1J includes a protection element 10F, a plurality of secondary battery cells 20, 20, ···, an external positive electrode terminal 30a, an external negative electrode terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. As shown in FIG. 10(b), the protection element 10F has a second fusible conductor 17 between the heating element 16 of the protection element 10F and the third terminal 13, and a third fusible conductor 18 between the heating element 16 and the second terminal 12. By providing the second fusible conductor 17 and the third fusible conductor 18 in the current path P1 of the protection element 10F C in addition to cutting off the second current path P2 C it is possible to surely cut off the first current path P1 C and construct an even more secure protection circuit.

[0067] FIG. 11 is a circuit diagram schematically showing an example of the configuration of a protection circuit according to a fourth embodiment of the present invention. The configuration of the protection circuit 1K in FIG. 11 is different from that of the protection circuit 1D in that the protection element 10D is installed between the external positive terminal 30a and a plurality of secondary battery cells 20, 20, ···. The other configuration of the protection circuit 1K in FIG. 11 is basically the same as that of the protection circuit 1G in FIG. 8(a). The same components are denoted by the same reference numerals and their description is omitted, and mainly the different parts will be described below.

[0068] As shown in FIG. 11, the protection circuit 1K includes a protection element 10D, a plurality of secondary battery cells 20, 20, ···, an external positive terminal 30a and an external negative terminal 30b, an auxiliary power source 40, a first control device 50, and a switch 60. The protection element 10D includes a first terminal 11, a second terminal 12, a first fusible conductor 15 having both ends connected to the first terminal 11 and the second terminal 12, a third terminal 13, and a first current path P1 between the third terminal 13 and the first terminal 11. D In the present embodiment, the heating element 16 is installed in the first current path P1 between the third terminal 13 and the first terminal 11. C However, the present invention is not limited to this, and it may be installed in the first current path between the third terminal 13 and the second terminal 12.

[0069] In the present embodiment, the positive terminal 40a of the auxiliary power source 40 is connected to the external positive terminal 30a, and the negative terminal 40b is connected to the switch 60. Also, the positive terminal 40a of the auxiliary power source 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. And the third terminal 13 of the protection element 10D is connected to the second current path P2 where the first terminal 11 and the second terminal 12 of the protection element 10D are connected via the auxiliary power source 40 and the switch 60. D Also, the poles of the second current path P2 where the first terminal 11 and the second terminal 12 of the protection element 10D are connected and the pole on the side connected to the third terminal 13 of the auxiliary power source 40 may be connected with the same poles. D

[0070] Even with this protection circuit 1K, similar to the protection circuit 1G, the switch 60 is switched to be energized by a signal from the first control device 50, the heating element 16 of the protection element 10D generates heat, and the first fusible conductor 15 is blown to cut off the connection between the plurality of secondary battery cells 20, 20,... and the external positive terminal 30a. Therefore, even when a large voltage and a large current occur in the second current path P2 D the withstand voltage can be sufficiently ensured by reducing the voltage applied to the heating element 16 in the first current path P1 D and high safety can be achieved.

[0071] FIG. 12 is a diagram showing another modification of the protection circuit 1G in FIG. 8(a). The configuration of the protection circuit 1L in FIG. 12 is basically the same as the configuration of the protection circuit 1G in FIG. 8(a). The same components are denoted by the same reference numerals and their descriptions are omitted, and mainly the different parts will be described below. As shown in FIG. 12, the first control device 50 may receive a signal from a control device 91 such as an ECU mounted on the vehicle and output a signal to the switch 60 based on the signal. For example, when the control device 91 detects either or both of an abnormality in the voltage of the plurality of secondary battery cells 20, 20,... and other abnormalities occurring in the vehicle, it outputs a signal to the switch 60. According to this modification, not only an abnormality in the voltage of the plurality of secondary battery cells 20, 20,... but also various abnormalities occurring in the vehicle are detected, and the connection between the plurality of secondary battery cells 20, 20,... and the external negative terminal 30b is cut off. Therefore, higher safety can be achieved by cooperating with the control device 91 in the vehicle.

[0072] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Industrial Applicability

[0073] The protection circuit of the present invention can be applied to charge and discharge circuits of various secondary batteries such as lithium-ion batteries. In particular, it is suitable for charge and discharge circuits of moving bodies that use secondary batteries as power sources, such as vehicles (e.g., electric vehicles (EVs)), ships, and airplanes.

Explanation of Signs

[0074] 1A Protection circuit 1B Protection circuit 1C Protection circuit 1D Protection circuit 1E Protection circuit 1F Protection circuit 1G Protection circuit 1H Protection circuit 1J Protection circuit 1K Protection circuit 1L Protection circuit 2 Fuse element 2a One end 2b The other end 2c Cutting part 3a Heating element 3b Convex member 3c Convex part 3 Movable member 4 Concave member 4a Concave part 5 Pressing means 6 Case 6a First terminal 6b Second terminal 10 Protection element 10A Protection element 10B Protection element 10C Protection element 10D Protection element 10E Protection element 10F Protection element 11 First terminal 12 Second terminal 13 Third terminal 14 Fourth terminal 15 First soluble conductor 15a One end 15b Multiple ends 16 Heating element 17 Second soluble conductor 18 Third soluble conductor 20 Secondary battery cell 20a Positive electrode terminal 20b Negative electrode terminal 30a External positive electrode terminal 30b External negative electrode terminal 40 Auxiliary power source 40a Positive electrode terminal 40b Negative electrode terminal 50 First control device 60 Switch 80 Second control device 90 Switch 91 Control device

Claims

1. A protection element having a first terminal, a second terminal, a first fusible conductor having both ends connected to the first terminal and the second terminal, a third terminal, a fourth terminal, and a heating element installed in a first current path between the third terminal and the fourth terminal; A plurality of secondary battery cells connected in series; An external positive terminal and an external negative terminal; An auxiliary power source; a control device that monitors the voltages of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; A switch for switching energization in response to a signal from the control device, the control device is connected to the plurality of secondary battery cells; the first terminal and the second terminal of the protection element are installed in a second current path between positive terminals of the secondary battery cells and the external positive terminal or between negative terminals of the secondary battery cells and the external negative terminal; the third terminal and the fourth terminal of the protection element are connected in series with the auxiliary power supply and the switch in a loop shape; the second current path, in which the first terminal and the second terminal of the protection element are connected, is connected to a third current path, which is connected from the third terminal to the fourth terminal via the auxiliary power supply and the switch; A protection circuit in which the switch is switched to conduct electricity by the signal from the control device, the heating element of the protection element heats up, and the first fusible conductor melts to disconnect between the multiple secondary battery cells and the external positive terminal or between the multiple secondary battery cells and the external negative terminal.

2. The protection circuit according to claim 1 , further comprising a second fusible conductor between the heating element and the third terminal of the protection element or between the heating element and the fourth terminal of the protection element.

3. The protection circuit of claim 1 , further comprising a second fusible conductor between the heating element and the third terminal of the protection element, and a third fusible conductor between the heating element and the fourth terminal of the protection element.

4. A protection element having a first terminal, a second terminal, a first fusible conductor having both ends connected to the first terminal and the second terminal, a third terminal, and a heating element installed in a first current path between the third terminal and the first terminal or the second terminal; A plurality of secondary battery cells connected in series; An external positive terminal and an external negative terminal; An auxiliary power source; a control device that monitors the voltages of the plurality of secondary battery cells, detects an abnormality, and outputs a signal; A switch for switching energization in response to a signal from the control device, the control device is connected to the plurality of secondary battery cells; the first terminal and the second terminal of the protection element are installed in a second current path between positive terminals of the secondary battery cells and the external positive terminal or between negative terminals of the secondary battery cells and the external negative terminal; a protection circuit in which the third terminal of the protection element is connected to the second current path to which the first terminal and the second terminal of the protection element are connected, via the auxiliary power source and the switch, the switch is switched to be conductive by the signal from the control device, the heating element of the protection element generates heat, and the first fusible conductor melts, thereby insulating between the multiple secondary battery cells and the external positive terminal or between the multiple secondary battery cells and the external negative terminal.

5. The protection circuit of claim 4 , further comprising a second fusible conductor between the heating element and the third terminal of the protection element.

6. The protection circuit according to claim 4, further comprising a second fusible conductor between the heating element and the third terminal of the protection element, 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, wherein a pole of the second current path to which the first terminal and the second terminal of the protection element are connected is connected with a pole opposite to a pole connected to the third terminal of the auxiliary power supply, with the same polarity.

8. The protection circuit according to any one of claims 1 to 7, wherein the first fusible conductor is a laminate including a low melting point metal layer and a high melting point metal layer.

9. 9. The protection circuit according to claim 8, wherein the low melting point metal layer is made of Sn or an alloy mainly composed of Sn, and the high melting point metal layer is made of Ag or Cu, or an alloy mainly composed of Ag or Cu.

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