Power supply control device

Abstract

To provide a power supply control device capable of preventing the temperature of a wire from increasing to a high temperature even when a fault occurs in a semiconductor switch.SOLUTION: A power supply control device 10 controls power supply via a wire W. A fuse 20 and a semiconductor switch 30 are arranged in a current path of wire current flowing through the wire W. The fuse 20 and the semiconductor switch 30 are attached to a circuit board. A plurality of terminals possessed by the fuse 20 are connected to the circuit board by solder. A fusion part is connected between two terminals among the plurality of terminals. The two terminals are arranged in the current path of the wire current. The fusion part is fused depending on the temperature of the fusion part. A microcomputer 22 instructs to turn off of the semiconductor switch 30 depending on the wire temperature of the wire W.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply control device. [Background technology]

[0002] Patent Document 1 discloses a device for a vehicle that prevents the temperature of an electric wire from rising to a high temperature. A current flows from the positive pole of a DC power source through the electric wire. In the device described in Patent Document 1, a semiconductor switch is disposed in a current path of the current flowing through the electric wire. The semiconductor switch is switched on or off by a control circuit. When the semiconductor switch is on, a current flows through the electric wire. When a current flows through the electric wire, the electric wire generates heat. When the amount of heat generated by the electric wire per unit time is greater than the amount of heat dissipated by the electric wire per unit time, the temperature of the electric wire rises.

[0003] When the semiconductor switch is on, the control circuit calculates the temperature of the electric wire based on the current value of the current flowing through the electric wire. When the calculated temperature exceeds a predetermined temperature, the control circuit switches the semiconductor switch off. This stops the flow of current through the electric wire and reduces the temperature of the electric wire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-283977 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, in the event of an on-fault in which the semiconductor switch is fixed on, when the calculated temperature of the electric wire exceeds a predetermined temperature, the control circuit cannot switch the semiconductor switch off. If the temperature of the electric wire rises to a temperature that greatly exceeds the predetermined temperature, the electric wire may deteriorate. Deterioration of the electric wire is, for example, an increase in the resistance value of the electric wire. If the resistance value of the electric wire increases, a large amount of power is consumed in the electric wire. In this case, power cannot be efficiently supplied through the electric wire.

[0006] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a power supply control device that can prevent the temperature of the electric wire from rising to a high temperature even if a failure occurs in the semiconductor switch. [Means for solving the problem]

[0007] A power supply control device according to one embodiment of the present disclosure is a power supply control device that controls power supply via an electric wire, and includes a fuse and a semiconductor switch that are arranged in a current path of an electric wire current flowing through the electric wire, a circuit board on which the fuse and the semiconductor switch are attached, and a processing unit that executes processing, wherein the fuse has a plurality of terminals connected to the circuit board by soldering and a fusing portion connected between two terminals among the plurality of terminals, the two terminals among the plurality of terminals are arranged in the current path, the fusing portion is melted in response to a temperature of the fusing portion, and the processing unit instructs the semiconductor switch to be switched off in response to the electric wire temperature of the electric wire. Effect of the Invention

[0008] According to the above aspect, even if a failure occurs in the semiconductor switch, the temperature of the electric wire can be prevented from increasing to a high temperature. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a main part of a power supply system according to a first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of the arrangement of fuses, switches, and a microcomputer. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] 4 is an explanatory diagram of the state of the terminals and the fusion portion as viewed from above in FIG. 3; [Figure 8] FIG. 2 is an explanatory diagram showing a state in which the fuse is attached to a circuit board. [Figure 9] FIG. 11 is another explanatory diagram showing the fuse attached to the circuit board. [Figure 10] FIG. 2 is a block diagram showing a main configuration of a microcomputer; [Figure 11] 10 is a flowchart showing a procedure of a power supply control process. [Figure 12] 10 is a flowchart showing a procedure for a wire protection process. [Figure 13] FIG. 2 is an explanatory diagram of timing relating to melting, interruption, and smoking. [Figure 14] FIG. 11 is a block diagram showing the configuration of a main part of a power supply system according to a second embodiment. [Figure 15] FIG. 11 is a block diagram showing a configuration of a main part of a power supply system according to a third embodiment. [Figure 16] FIG. 11 is a block diagram showing a configuration of a main part of a power supply system according to a fourth embodiment. [Figure 17] FIG. 13 is a block diagram showing a configuration of a main part of a power supply system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. At least a part of the embodiments described below may be arbitrarily combined.

[0011] (1) A power supply control device according to one embodiment of the present disclosure is a power supply control device that controls power supply via an electric wire, and includes a fuse and a semiconductor switch that are arranged in a current path of an electric wire current flowing through the electric wire, a circuit board to which the fuse and the semiconductor switch are attached, and a processing unit that executes processing, wherein the fuse has a plurality of terminals connected to the circuit board by soldering and a fusing portion connected between two terminals among the plurality of terminals, the two terminals among the plurality of terminals are arranged in the current path, the fusing portion is melted in response to a temperature of the fusing portion, and the processing unit instructs the semiconductor switch to be switched off in response to the electric wire temperature of the electric wire.

[0012] In the above embodiment, when the semiconductor switch is on, the wire current flows through the fuse, the semiconductor switch, and the wire. This causes the melting portion of the fuse and the wire to heat up. Therefore, when the temperature of the wire rises, the temperature of the melting portion of the fuse also rises. When the temperature of the wire is high, the semiconductor switch is switched off. This stops the flow of the wire current and reduces the temperature of the wire.

[0013] When an on-fault occurs in which the semiconductor switch is fixed on, and the wire temperature is high, the fusing portion of the fuse melts. This stops the flow of current through the wire, and the wire temperature drops. Therefore, even if an on-fault occurs in the semiconductor switch, the wire temperature can be prevented from rising to a high temperature.

[0014] (2) In a power supply control device according to one embodiment of the present disclosure, the processing unit instructs the semiconductor switch to be switched off when the temperature of the electric wire becomes equal to or higher than a temperature threshold, and when the semiconductor switch is on, the temperature of the electric wire becomes equal to or higher than the temperature threshold before the fusing portion melts.

[0015] In the above aspect, unless an ON failure occurs in the semiconductor switch, the semiconductor switch is switched off before the fusing portion is blown.

[0016] (3) In a power supply control device according to one aspect of the present disclosure, the fuse has a housing that covers a portion of the plurality of terminals and the melting portion, and the housing has a heat resistance of 300 degrees or more.

[0017] In the above embodiment, when multiple terminals of the fuse are soldered to a circuit board by the reflow method, hot air is blown onto the housing or infrared rays are irradiated onto the housing. This causes the temperature of the housing to rise. If the temperature of the housing is below X degrees, the housing will not deform or melt. Here, X is a positive real number. If the housing does not deform or melt, the shape of the housing is maintained. Heat resistance of 300 degrees or more means that X is 300 or more. Therefore, the housing will not melt or deform when hot air is blown onto it or infrared rays are irradiated onto it. As a result, the fuse is suitable for mounting on a circuit board by the reflow method.

[0018] (4) In a power supply control device according to one embodiment of the present disclosure, the circuit board has an insulating substrate, a plurality of through holes penetrating the insulating substrate, and a plurality of substrate platings covering the insulating substrate, and each of a plurality of terminals of the fuse is inserted into a plurality of through holes and connected to the plurality of substrate platings of the circuit board by the solder.

[0019] In the above embodiment, the plurality of terminals of the fuse are inserted into the plurality of through holes, and in this state, the plurality of terminals are connected by solder to the plurality of board platings of the circuit board.

[0020] (5) In a power supply control device according to an aspect of the present disclosure, each of the plurality of terminals has a metal body and tin terminal plating covering a surface of the metal body.

[0021] In the above embodiment, the surface of the metal body of each terminal is covered with a terminal plating made of tin. Solder usually contains a tin component. Therefore, the terminal having the terminal plating made of tin has high compatibility with the solder, i.e., high wettability. Therefore, the solder adheres strongly to the terminal.

[0022] (6) A power supply control device according to one embodiment of the present disclosure includes a switching circuit that switches the semiconductor switch on or off, and the switching circuit switches the semiconductor switch off when a voltage value across the fusion portion of the fuse becomes equal to or greater than a predetermined voltage value.

[0023] In the above embodiment, the higher the current value of the electric wire current, the higher the voltage value across the fusing portion. When the voltage value across the fusing portion is equal to or greater than the predetermined voltage value, i.e., when the current value of the electric wire current is large, the switching circuit switches the semiconductor switch off. Thus, excessive current is prevented from flowing through the electric wire.

[0024] (7) In a power supply control device according to an aspect of the present disclosure, the processing unit repeatedly calculates the wire temperature based on a voltage value across the melting portion of the fuse.

[0025] In the above aspect, the processor repeatedly calculates the wire temperature based on the voltage value across the fusing portion, and when the calculated wire temperature is equal to or higher than the temperature threshold, the semiconductor switch is switched off.

[0026] (8) In a power supply control device according to one embodiment of the present disclosure, the fuse has a housing covering a portion of the multiple terminals and the melting portion, each of the multiple terminals has a long, plate-shaped first plate portion partially covered by the housing and a second plate portion connected to the first plate portion, one end of each of the multiple terminals protrudes from a common side of the housing and the second plate portion protrudes from a portion of an end surface of the first plate portion protruding from the housing, the circuit board has a plurality of through holes, the second plate portion of each of the multiple terminals is inserted into the multiple through holes, and the first plate portion of each of the multiple terminals abuts against the circuit board.

[0027] In the above embodiment, the second plate portion protrudes from the tip surface of the first plate portion protruding from the housing, realizing a stepped structure. In the circuit board, a through hole is provided in the insulating substrate, and the inner surface and the peripheral portion of the through hole are covered with board plating in the insulating substrate. For example, a through hole having an area slightly larger than the cross-sectional area of ​​the second plate portion is provided. In this case, when the second plate portion is inserted into the through hole, the first plate portion does not pass through the through hole and comes into contact with the board plating covering the peripheral portion of the through hole. At this time, the housing is separated from the circuit board by the first plate portion. In this case, when the terminal is attached to the circuit board with solder, a fillet-shaped solder is easily formed. The formation of the fillet-shaped solder means that good attachment has been achieved.

[0028] [Details of the embodiment of the present disclosure] Specific examples of power supply systems according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0029] (Embodiment 1) <Power supply system configuration> FIG. 1 is a block diagram showing a configuration of a main part of a power supply system 1 in the first embodiment. The power supply system 1 is mounted on a vehicle C. The power supply system 1 includes a power supply control device 10, a DC power supply 11, and a load 12. The power supply control device 10 includes a fuse 20, a switch device 21, and a microcomputer (hereinafter, referred to as a microcomputer) 22. The switch device 21 is, for example, an IPD (Intelligent Power Device). The switch device 21 includes a semiconductor switch 30 and a drive circuit 31. The semiconductor switch 30 is an N-channel type FET (Field Effect Transistor). The DC power supply 11 is, for example, a battery. The load 12 is an electric device.

[0030] The negative electrode of the DC power supply 11 is grounded. The grounding is achieved, for example, by connection to the body of the vehicle C. The positive electrode of the DC power supply 11 is connected to one end of a fuse 20. The other end of the fuse 20 is connected to the drain of a semiconductor switch 30. The source of the semiconductor switch 30 is connected to one end of an electric wire W. The other end of the electric wire W is connected to one end of a load 12. The other end of the load 12 is grounded. The gate of the semiconductor switch 30 is connected to a drive circuit 31. The drive circuit 31 is further connected to a microcomputer 22.

[0031] The microcomputer 22 outputs a high-level voltage or a low-level voltage to the drive circuit 31. When the microcomputer 22 switches the output voltage from a low-level voltage to a high-level voltage, the drive circuit 31 switches the semiconductor switch 30 from off to on. When the microcomputer 22 switches the output voltage from a high-level voltage to a low-level voltage, the drive circuit 31 switches the semiconductor switch 30 from on to off. The drive circuit 31 functions as a switching circuit.

[0032] When the semiconductor switch 30 is on, the resistance between the drain and source of the semiconductor switch 30 is sufficiently small. Therefore, a current can flow through the drain and the source. When the semiconductor switch 30 is off, the resistance between the drain and the source of the semiconductor switch 30 is sufficiently large. Therefore, no current flows through the drain and the source.

[0033] When the drive circuit 31 switches the semiconductor switch 30 on, a current flows from the positive electrode of the DC power supply 11 to the fuse 20, the semiconductor switch 30, the wire W, and the load 12 in this order. Hereinafter, the current flowing through the wire W will be referred to as the wire current. The current value of the wire current will be referred to as the wire current value. The fuse 20 and the semiconductor switch 30 are arranged in the current path of the wire current. When the wire current flows, power is supplied to the load 12. When power is supplied to the load 12, the load 12 operates. When the drive circuit 31 switches the semiconductor switch 30 off, the flow of the wire current stops. As a result, the power supply to the load 12 stops, and the load 12 stops operating. In the power supply control device 10, the drive circuit 31 controls the power supply to the load 12 through the wire W by switching the semiconductor switch 30 on or off.

[0034] When a current flows through fuse 20, fuse 20 generates heat. For fuse 20, if the amount of heat generated per unit time exceeds the amount of heat dissipation per unit time, the fuse temperature of fuse 20 increases. For fuse 20, if the amount of heat generated per unit time is less than the amount of heat dissipation per unit time, the fuse temperature decreases. Similarly, when a wire current flows, wire W generates heat. For wire W, if the amount of heat generated per unit time exceeds the amount of heat dissipation per unit time, the wire temperature of wire W increases. For fuse 20, if the amount of heat generated per unit time is less than the amount of heat dissipation per unit time, the wire temperature decreases.

[0035] As described later, the microcomputer 22 repeatedly calculates the wire temperature based on the wire current value. When the calculated wire temperature reaches or exceeds a certain temperature threshold, the microcomputer 22 switches the output voltage from a high-level voltage to a low-level voltage. This causes the drive circuit 31 to switch the semiconductor switch 30 from on to off.

[0036] When a wire current flows, the current flows through the fuse 20. Therefore, when the wire temperature rises, the fuse temperature also rises. When the fuse temperature reaches or exceeds a certain melting temperature, the fuse 20 melts. When the fuse 20 melts, the flow of current through the fuse 20 stops. As a result, the flow of wire current stops. The wire temperature when the fuse temperature is the melting temperature is referred to as the reference temperature. The reference temperature exceeds the temperature threshold.

[0037] For example, if both ends of the load 12 are short-circuited while the semiconductor switch 30 is on, the wire current rises rapidly, and the wire temperature and fuse temperature rise. In the absence of an on-fault in which the semiconductor switch 30 is fixed on, when the wire temperature reaches or exceeds the temperature threshold, the drive circuit 31 switches the semiconductor switch 30 off. As a result, the flow of the wire current stops, and the wire temperature drops.

[0038] In the event that an on-fault occurs, the fuse 20 melts when the wire temperature reaches or exceeds the reference temperature. As a result, the flow of current through the wire stops and the wire temperature drops. Therefore, even if an on-fault occurs in the semiconductor switch 30, the wire temperature can be prevented from rising to a high temperature that exceeds the reference temperature.

[0039] <Arrangement of fuse 20, switch 21, and microcomputer 22> Fig. 2 is an explanatory diagram of the arrangement of the fuse 20, the switch device 21, and the microcomputer 22. The power supply control device 10 further has a rectangular circuit board B. Fig. 2 shows a plan view of the circuit board B. The switch device 21 and the microcomputer 22 are integrated circuit elements. The fuse 20, the switch device 21, and the microcomputer 22 are attached to the board surface of the circuit board B. With respect to the board, the board surface is the wide surface and is different from the end surface. The attachment of the switch device 21 corresponds to the attachment of the semiconductor switch 30. In addition, when the switch device 21 is not an integrated circuit element, the semiconductor switch 30 and one or more components constituting the drive circuit 31 are attached to the surface of the circuit board B. In addition, the microcomputer 22 may be disposed on the surface of a circuit board different from the circuit board B.

[0040] <Fuse 20 Configuration> Fig. 3 is a front view of fuse 20. Fig. 4 is a side view of fuse 20. Fuse 20 has a resin housing 40 and two terminals 41. Each terminal 41 is conductive. In fuse 20, the two terminals 41 protrude from a common surface of housing 40.

[0041] FIG. 5 is a cross-sectional view of a terminal 41. Each terminal 41 has a long plate-shaped metal body 50. In each terminal 41, two plate surfaces of the metal body 50 are covered with terminal plating 51 made of tin (Sn). At the end faces of each terminal 41, the metal body 50 is exposed. The metal body 50 and the terminal plating 51 are conductive. The metal body 50 is manufactured using, for example, a zinc alloy. In drawings other than FIG. 5, the metal body 50 and the terminal plating 51 are omitted. The terminal plating 51 may cover a surface of the metal body 50 different from the plate surface, for example, an end surface located on the left or right side in FIG.

[0042] FIG. 6 is a cross-sectional view of the fuse 20. As shown in FIGS. 3, 4 and 6, the housing 40 is box-shaped with one side open. Each of the two terminals 41 is partially covered by the housing 40. As described above, the two terminals 41 protrude from a common side of the housing 40. Here, the common side is an open side. In the housing 40, the common side is located on the lower side of FIGS. 3, 4 and 6. As shown in FIG. 6, the two terminals 41 are arranged in a row inside the housing 40. The fuse 20 further has a rod-shaped fusion portion 42. The fusion portion 42 is connected between the two terminals 41. The fusion portion 42 is conductive. The fusion portion 42 is also covered by the housing 40.

[0043] Fig. 7 is an explanatory diagram of the state of the two terminals 41 and the fusion portion 42 as viewed from above in Fig. 3. As shown in Figs. 6 and 7, each terminal 41 has a long plate shape. The plate surfaces of the two terminals 41 are aligned, and Fig. 6 shows the plate surfaces of the two terminals 41. One end of each terminal 41 protrudes from a common surface (open surface) of the housing 40 toward the lower side in Fig. 6. It is preferable that the plate surfaces of the two terminals 41 are located on the same plane.

[0044] Each terminal 41 is shaped like a long plate, so fuse 20 is a blade-type fuse. In general, the cross-sectional area of ​​the terminals of a blade-type fuse is larger than that of a chip-type fuse. For this reason, a blade-type fuse can be used as the fuse for a circuit through which a large current flows under normal conditions.

[0045] In each terminal 41, an end of a long plate-shaped first plate portion 61 is connected to an end of a long plate-shaped second plate portion 62. A part of the first plate portion 61 is covered by the housing 40. For each of the two terminals 41, a first end of the first plate portion 61 protrudes downward in FIG. 6 from the common surface of the housing 40 described above. The common surface of the housing 40 and a tip surface of the first end of the first plate portion 61 are parallel. For the two terminals 41, the tip surfaces of the first ends of the two first plate portions 61 are located on the same plane.

[0046] The parallelism of the common surface and the tip surface does not necessarily mean perfect parallelism, but may mean substantial parallelism. Therefore, the state in which the common surface and the tip surface are parallel also includes a state in which the angle between the common surface and the tip surface is within the design error range. In addition, the two tip surfaces being located on the same plane means that there is substantially no step between the two tip surfaces. Therefore, when the step between the two tip surfaces is within the design error range, the two tip surfaces are located on the same plane.

[0047] In each terminal 41, the second plate portion 62 protrudes from a portion of the tip surface of the first end of the first plate portion 61 along the length direction of the first plate portion 61. The cross-sectional area of ​​the second plate portion 62 is smaller than the cross-sectional area of ​​the first plate portion 61. The second plate portion 62 is thinner than the first plate portion 61. The thicknesses of the first plate portion 61 and the second plate portion 62 are the same. The plate surfaces of the first plate portion 61 and the second plate portion 62 are continuous. The length directions of the first plate portion 61 and the second plate portion 62 are the same, and are the up-down direction in Figures 3, 4, and 6. The cross-sectional areas of the first plate portion 61 and the second plate portion 62 are the areas of the cross sections obtained by cutting the first plate portion 61 and the second plate portion 62 in the width direction, i.e., the left-right direction in Figures 3, 4, and 6.

[0048] Incidentally, the agreement of the thicknesses of the first plate portion 61 and the second plate portion 62 does not necessarily mean a perfect agreement, but may be a substantial agreement. Therefore, the state in which the thicknesses of the first plate portion 61 and the second plate portion 62 are the same also includes a state in which the difference between the two thicknesses is within the error range. Furthermore, the agreement of the two length directions does not necessarily mean a perfect agreement, but may be a substantial agreement. Therefore, the state in which the two length directions are the same also includes a state in which the angle between the two length directions is within the error range.

[0049] For each of the two terminals 41, the second plate portion 62 protrudes from the center of the arrangement direction of the two terminals 41 on the tip surface of the first end of the first plate portion 61. The arrangement direction is the left-right direction in Fig. 6. As shown in Figs. 3 and 4, the tip portion of the second plate portion 62 has a truncated pyramid shape. The cross-sectional area of ​​the tip portion of the second plate portion 62 is large at the portion close to the housing 40 and small at the portion far from the housing 40.

[0050] As shown in Figs. 6 and 7, the rod-shaped fusing portion 42 is disposed between the first plate portions 61 of the two terminals 41. One end of the fusing portion 42 is connected to an end face of the first plate portion 61 of one terminal 41. The other end of the fusing portion 42 is connected to an end face of the first plate portion 61 of the other terminal 41. The two end faces to which the fusing portion 42 is connected face each other. The fusing portion 42 is curved and forms a V-shape as a whole. In the example of Fig. 6, the fusing portion 42 is curved to the upper side of Fig. 6. The shape of the fusing portion 42 is not limited to a V-shape, and may be, for example, an S-shape.

[0051] As shown in Figs. 6 and 7, the housing 40 has two openings 40a on a surface opposite to the common surface described above, i.e., the upper surface in Fig. 6. The second ends of the first plate portions 61 of the two terminals 41 face the two openings 40a. The user of the fuse 20, for example, passes two lead rods of a tester through the two openings 40a. In this state, the user applies the two lead rods of the tester to the two terminals 41 of the fuse 20. The tester, for example, measures the resistance between the two terminals 41. The user can check whether the fusing portion 42 has been blown based on the measured resistance.

[0052] <Fuse 20 installation status> FIG. 8 is an explanatory diagram showing a state in which the fuse 20 is attached to the circuit board B. FIG. 9 is another explanatory diagram showing a state in which the fuse 20 is attached to the circuit board B. The circuit board B is a so-called printed circuit board. The fuse 20 is attached to the circuit board B by solder H. FIGS. 8 and 9 show a state after the fuse 20 is attached to the circuit board B by solder H. FIGS. 8 and 9 show a cross section of the circuit board B. As shown in FIGS. 8 and 9, the circuit board B has an insulating board 70. The insulating board 70 is provided with two through holes 70a penetrating from the front plate surface to the back plate surface. The number of the through holes 70a is equal to or greater than the number of the terminals 41 of the fuse 20. The opening of the through hole 70a is circular. In FIGS. 8 and 9, the upper plate surface of the insulating board 70 is the front plate surface, and the lower plate surface is the back plate surface.

[0053] A plurality of conductive wiring patterns 72 are arranged on the front plate surface of the insulating substrate 70. A plurality of wiring patterns 72 are also arranged on the rear plate surface of the insulating substrate 70. In the circuit board B, the inner surface of each through hole 70a is covered with a substrate plating 71. The substrate plating 71 is conductive. The peripheral portion of the through hole 70a on each of the front plate surface and the rear plate surface is covered with the substrate plating 72. In addition to the inner surface of the through hole 70a, each substrate plating 71 covers the peripheral portion of the through hole 70a on each of the front plate surface and the rear plate surface via the substrate plating 72. In FIG. 8, the substrate plating 71 covers the peripheral portion of the through hole 70a from above the substrate plating 72 and covers the peripheral portion of the through hole 70a from below the substrate plating 72.

[0054] The substrate plating 71 contains, for example, a tin component. The wiring pattern 72 is made of, for example, copper. The substrate plating 71 is in contact with the wiring pattern 72 and is electrically connected to the wiring pattern 72. The substrate plating 71 is covered with a resist 73 having insulating properties, except for the inner surface and peripheral portion of the through hole 70a.

[0055] The area of ​​the through hole 70a is slightly larger than the cross-sectional area of ​​the second plate portion 62 of the terminal 41. Therefore, the second plate portion 62 of the terminal 41 can be inserted into the through hole 70a. Since the width of the first plate portion 61 is sufficiently long, when the second plate portion 62 is inserted into the through hole 70a, the first plate portion 61 of the terminal 41 does not pass through the through hole 70a but comes into contact with the board plating 71 covering the periphery of the through hole 70a. Since the tip surfaces of the first ends of the two first plate portions 61 are located on the same plane, the fuse 20 is supported by the circuit board B in a stably state.

[0056] When attaching the fuse 20 to the circuit board B, a paste-like solder H is applied onto the board plating 71 covering the front plate surface of the insulating board 70. With the solder H applied onto the board plating 71, the second plate portions 62 of the two terminals 41 are inserted into the two through holes 70a from the front side of the insulating board 70, i.e., from the upper side in FIGS. 8 and 9. At this time, the first plate portions 61 of the two terminals 41 are supported by the board plating 71 covering the front plate surface. A part of the second plate portion 62 is exposed from the back plate surface of the circuit board B.

[0057] In this state, the fuse 20 and the circuit board B are passed through a reflow oven. In the reflow oven, hot air is blown onto the fuse 20 and the circuit board B, or infrared rays are irradiated onto the fuse 20 and the circuit board B. This melts the paste-like solder H. The solder H connects the terminal 41 to the board plating 71 of the circuit board B. Specifically, as shown in Figs. 8 and 9, a portion of the solder H is bonded around the axis of the first plate portion 61 to the plate surface and end surface of the first plate portion 61 of the terminal 41 exposed from the housing 40, and is also bonded to the board plating 71 covering the front plate surface of the insulating board 70.

[0058] Furthermore, a portion of the molten solder H enters the through hole 70a and adheres to the board plating 71 covering the inner surface of the through hole 70a and to the plate surface and end surface of the second plate portion 62 of the terminal 41. The solder H is conductive. The terminal 41 and the board plating 71 are electrically connected by the solder H. The two terminals 41 of the fuse 20 are connected by the solder H to the two board platings 71 of the circuit board B.

[0059] As described above, in the power supply control device 10, the fuse 20 is attached to the circuit board B. The two terminals 41 are inserted into the two through holes 70a, respectively. In this state, the two terminals 41 are connected to the two board platings 71 by the solder H, respectively.

[0060] With respect to the fuse 20, one terminal 41 corresponds to one end connected to the positive electrode of the DC power supply 11. The other terminal 41 corresponds to one end connected to the drain of the semiconductor switch 30. As described above, the wire current flows via the fuse 20. In the fuse 20, the wire current flows in the order of the terminal 41, the fusing portion 42, and the terminal 41. The two terminals 41 and the fusing portion 42 are disposed in the current path of the wire current.

[0061] When a current flows through the fusion portion 42, the fusion portion 42 heats up. Heat generation in the fuse 20 is heat generation in the fusion portion 42. The fuse temperature is the temperature of the fusion portion 42. When the amount of heat generated per unit time for the fusion portion 42 exceeds the amount of heat dissipated per unit time, the fuse temperature rises. When the amount of heat generated per unit time is less than the amount of heat dissipated per unit time, the fuse temperature falls. When the fuse temperature reaches or exceeds the melting temperature, the fusion portion 42 melts down. As a result, the flow of current through the fuse 20 stops.

[0062] <Heat resistance of housing 40> In one example of the reflow method, circuit board B on which fuse 20 is disposed passes through a first region and then a second region in a reflow furnace. The temperature in the first region is in the range of 170°C to 190°C. Circuit board B is in the first region for 80 to 140 seconds. The temperature in the second region is in the range of 230°C to 250°C. Circuit board B is in the second region for 60 to 90 seconds.

[0063] When the fuse 20 is attached to the circuit board B using the reflow method, hot air is blown onto the housing 40 or infrared rays are irradiated onto the housing 40. At this time, the temperature of the housing 40 rises. If the temperature of the housing 40 is below X degrees, the housing 40 will not deform or melt. Here, X is a positive real number. If the housing 40 does not deform or melt, the shape of the housing 40 is maintained. The housing 40 has a heat resistance of 250 degrees or more. With respect to the housing 40, a heat resistance of 250 degrees or more means that X is 250 or more.

[0064] When the housing 40 has a heat resistance of 250 degrees or more, the housing 40 does not deform or melt when exposed to hot air or infrared radiation, and the shape of the housing 40 is maintained. This makes the fuse 20 suitable for mounting to the circuit board B by a reflow method. An example of a heat-resistant resin used in manufacturing the housing 40 is nylon resin.

[0065] It is preferable that housing 40 has a heat resistance of 300 degrees or more. With respect to housing 40, heat resistance of 300 degrees or more means that X is 300 or more. When housing 40 has a heat resistance of 300 degrees or more, fuse 20 is more suitable for attachment to circuit board B by a reflow method.

[0066] <Heat resistance of Fuse 20> When the temperature of the fuse 20 is Y degrees or less, the fusing characteristic (see FIG. 13) of the fuse 20 does not change substantially, and the long-term reliability does not decrease substantially. The fuse 20 has a heat resistance of 250 degrees or more. When the temperature of the fuse 20 is 250 degrees or more, the heat resistance of 250 degrees or more means that Y is 250 or more. Not only the housing 40 but also the fuse 20 has a heat resistance of 250 degrees or more. Therefore, when the temperature of the fuse 20 is 250 degrees or less, the fusing characteristic does not change substantially, and the long-term reliability does not decrease substantially. The fusing characteristic indicates the relationship between the current value of the current flowing through the fuse 20 and the fusing time from when the current flows to when the fusing part 42 melts. The fusing characteristic indicates the fusing time corresponding to various current values. The long-term reliability is the lifespan during which the fuse 20 functions normally according to the specifications. It is not preferable that the lifespan of the fuse 20 is decreased by attaching the fuse 20 by the reflow method.

[0067] It is preferable that fuse 20 also has a heat resistance of 300 degrees or more. With respect to fuse 20, a heat resistance of 300 degrees or more means that Y is 300 or more. When fuse 20 has a heat resistance of 300 degrees or more, the configuration of fuse 20 is more suitable for attachment to circuit board B by a reflow method.

[0068] <Effects of Fuse 20> As described above, in each terminal 41, the surface of the metal body 50 is covered with the terminal plating 51 made of tin. The solder H usually contains a tin component. Therefore, the solder H has a high affinity, or so-called wettability, for the terminals 41 having the terminal plating 51 made of tin. Therefore, the solder H adheres strongly to the terminals 41. The terminal plating 51 is not limited to being made of tin, but may be made of, for example, an alloy containing a tin component.

[0069] As described above, in each terminal 41, the second plate portion 62 protrudes from the tip surface of the first plate portion 61, realizing a stepped structure. For each of the two terminals 41, the first plate portion 61 does not pass through the through hole 70a and abuts on the board plating 71 on the insulating board 70. For this reason, the housing 40 is separated from the circuit board B. In this case, when the terminals 41 are attached to the circuit board B with the solder H, the fillet-shaped solder H is likely to be formed. The formation of the fillet-shaped solder H means that good attachment has been achieved.

[0070] Furthermore, terminals 41 are inserted into through holes 70a with paste-like solder H applied onto substrate plating 71. As described above, because of the stepped structure, when terminals 41 are inserted into through holes 70a, housing 40 does not come into contact with paste-like solder H. For this reason, when solder H is melted by a reflow method, there is a low possibility that ball-like solder H will be formed.

[0071] As described above, the cross-sectional area of ​​the second plate portion 62 of the terminal 41 is smaller than that of the first plate portion 61, and the second plate portion 62 is thinner than the first plate portion 61. Therefore, a through hole having a small area can be used as the through hole 70a. In this case, the gap between the second plate portion 62 and the through hole 70a is small. Therefore, even if hot air is blown onto the housing 40, the second plate portion 62, i.e., the fuse 20, does not tilt significantly, and the housing 40 stands approximately vertically to the plate surface of the circuit board B. As a result, when mounting is performed by the reflow method, there is no need to fix the housing 40 in an approximately vertical state using a jig, and inexpensive mounting can be achieved.

[0072] <Detailed configuration of power supply control device 10> Regarding the semiconductor switch 30 shown in FIG. 1, when the voltage of the gate, whose reference potential is the potential of the source, is equal to or higher than a certain voltage, the state is on. When the voltage of the gate, whose reference potential is the potential of the source, is lower than the certain voltage, the state is off. When the output voltage of the microcomputer 22 is switched from a low-level voltage to a high-level voltage, the drive circuit 31 increases the voltage of the gate, whose reference potential is the ground potential. As a result, the voltage of the gate, whose reference potential is the potential of the source, increases to a voltage equal to or higher than the certain voltage, and the semiconductor switch 30 is switched on.

[0073] When the output voltage of the microcomputer 22 switches from a high-level voltage to a low-level voltage, the drive circuit 31 lowers the gate voltage, the reference potential of which is the ground potential, so that the gate voltage, the reference potential of which is the source potential, drops to a voltage below a certain voltage, and the semiconductor switch 30 switches off.

[0074] The switch device 21 further includes a current detection unit 32. The current detection unit 32 is connected to the drain of the semiconductor switch 30. The current detection unit 32 is further connected to the microcomputer 22 and the drive circuit 31, respectively.

[0075] The current detection unit 32 detects the wire current value. Specifically, the current detection unit 32 draws in a current from the drain of the semiconductor switch 30. The current value of the current drawn by the current detection unit 32 is expressed as (wire current value) / (predetermined number). The current detection unit 32 generates analog current value information indicating the wire current value based on the drawn current. The analog current value information is, for example, a voltage value proportional to the wire current value. The current detection unit 32 outputs the analog current value information to the microcontroller 22 and the drive circuit 31.

[0076] When the wire current value is less than a certain current threshold, the drive circuit 31 switches the semiconductor switch 30 on or off according to the output voltage of the microcomputer 22, as described above. When the wire current value becomes equal to or greater than the current threshold, the drive circuit 31 switches the semiconductor switch 30 off regardless of the output voltage of the microcomputer 22. This prevents the wire current value from exceeding the current threshold. After switching the semiconductor switch 30 off regardless of the output voltage of the microcomputer 22, the drive circuit 31 keeps the semiconductor switch 30 off until a predetermined condition is satisfied. The predetermined condition is, for example, that the output voltage of the microcomputer 22 switches from a low-level voltage to a high-level voltage.

[0077] 10 is a block diagram showing the main configuration of the microcomputer 22. The microcomputer 22 has an output unit 80, an A / D conversion unit 81, a storage unit 82, and a control unit 83. These are connected to an internal bus 84. The output unit 80 is further connected to a drive circuit 31. The A / D conversion unit 81 is further connected to a current detection unit 32.

[0078] The output unit 80 outputs a high-level voltage or a low-level voltage to the drive circuit 31. The output voltage of the microcontroller 22 described above is the output voltage of the output unit 80. The control unit 83 instructs the output unit 80 to switch the semiconductor switch 30 on. In this case, the output unit 80 switches the output voltage to a high-level voltage. As a result, the drive circuit 31 switches the semiconductor switch 30 on. The control unit 83 instructs the output unit 80 to switch the semiconductor switch 30 off. In this case, the output unit 80 switches the output voltage to a low-level voltage. As a result, the drive circuit 31 switches the semiconductor switch 30 off.

[0079] Analog current value information indicating the wire current value is input to the A / D conversion unit 81. The A / D conversion unit 81 converts the analog current value information into digital current value information. The digital current value information converted by the A / D conversion unit 81 is acquired by the control unit 83. The wire current value indicated by the current value information acquired by the control unit 83 substantially coincides with the wire current value at the time of acquisition.

[0080] The memory unit 82 is composed of, for example, a volatile memory and a non-volatile memory. A computer program P is stored in the memory unit 82. The control unit 83 has processing elements that execute processes and functions as a processing unit. The processing elements of the control unit 83 execute the computer program P to perform power supply control processing, electric wire protection processing, and the like. The power supply control processing is processing that controls the power supply to the load 12 via the electric wire W. The electric wire protection processing is processing that protects the electric wire W from smoke generation.

[0081] The computer program P may be stored in the storage medium A so that the processing element of the control unit 83 can read it. In this case, the computer program P read from the storage medium A by a reading device (not shown) is written to the storage unit 82. The storage medium A is an optical disk, a flexible disk, a magnetic disk, a magneto-optical disk, a semiconductor memory, or the like. The optical disk is a CD (Compact Disc)-ROM (Read Only Memory), a DVD (Digital Versatile Disc)-ROM, a BD (Blu-ray (registered trademark) Disc), or the like. The magnetic disk is, for example, a hard disk. The computer program P may also be downloaded from a device (not shown) connected to a communication network (not shown), and the downloaded computer program P may be written to the storage unit 82.

[0082] The number of processing elements included in the control unit 83 is not limited to one, and may be two or more. In this case, the multiple processing elements may cooperate with each other to execute the power supply control process, the power line protection process, and the like in accordance with the computer program P.

[0083] The memory unit 82 stores the value of a prohibition flag. The value of the prohibition flag is either 0 or 1, and is changed by the control unit 83. The prohibition flag value "0" indicates a state in which switching the semiconductor switch 30 on or off is permitted. When the semiconductor switch 30 is off, the value of the prohibition flag is changed from 0 to 1. The prohibition flag value "1" indicates a state in which switching the semiconductor switch 30 on is prohibited.

[0084] <Power supply control processing> 11 is a flowchart showing the procedure of the power supply control process. In the power supply control process, the control unit 83 determines whether the value of the prohibition flag is 1 or not (step S1). If the value of the prohibition flag is not 1, the value of the prohibition flag is 0. If the control unit 83 determines that the value of the prohibition flag is 1 (S1: YES), it executes step S1 again and waits until the value of the prohibition flag becomes 0.

[0085] When the control unit 83 determines that the value of the prohibition flag is not 1 (S1: NO), the control unit 83 determines whether or not to operate the load 12 (step S2). In step S2, for example, when an operation signal indicating operation of the load 12 is input to the input unit of the microcomputer 22, the control unit 83 determines to operate the load 12. When an operation signal is not input to the input unit, the control unit 83 determines not to operate the load 12.

[0086] When the control unit 83 determines not to operate the load 12 (S2: NO), it determines whether or not to stop the operation of the load 12 (step S3). In step S3, for example, when a stop signal indicating the stop of the operation of the load 12 is input to the input unit of the microcomputer 22, the control unit 83 determines to stop the operation of the load 12. When a stop signal is not input to the input unit, the control unit 83 determines not to stop the operation of the load 12.

[0087] When the control unit 83 determines not to stop the operation of the load 12 (S3: NO), it executes step S1 again. When the value of the prohibition flag is 0, it waits until the timing to operate the load 12 or the timing to stop the operation of the load 12 arrives.

[0088] When the control unit 83 determines that the load 12 is to be operated (S2: YES), it instructs the output unit 80 to switch the semiconductor switch 30 to ON (step S4). When an OFF fault in which the semiconductor switch 30 is fixed to OFF has not occurred, when the control unit 83 executes step S4, the drive circuit 31 switches the semiconductor switch 30 to ON. This causes a wire current to flow, and the load 12 is operated.

[0089] When the control unit 83 determines that the operation of the load 12 should be stopped (S3: YES), it instructs the output unit 80 to switch the semiconductor switch 30 to OFF (step S5). When the control unit 83 executes step S5 in a case where an ON fault does not occur in the semiconductor switch 30, the drive circuit 31 switches the semiconductor switch 30 to OFF. This stops the flow of the electric wire current, and the load 12 stops operating.

[0090] After the control unit 83 executes step S4 or step S5, the control unit 83 ends the power supply control process. After that, the control unit 83 executes the power supply control process again. As described above, in the power supply control device 10, the drive circuit 31 switches the semiconductor switch 30 on or off to control the power supply to the load 12 via the electric wire W. When the value of the prohibition flag is 1, the drive circuit 31 does not switch the semiconductor switch 30 on, and the semiconductor switch 30 is maintained off.

[0091] <Calculation of wire temperature> In the wire protection process, the control unit 83 calculates the wire temperature based on the wire current value. A method for calculating the wire temperature will be described below. The control unit 83 repeatedly calculates the temperature difference between the wire temperature of the wire W and the environmental temperature of the environment in which the wire W is placed. Specifically, the control unit 83 calculates the temperature difference based on a previously calculated previous temperature difference, the environmental temperature, and the wire current value. The control unit 83 calculates the wire temperature by adding the calculated temperature difference to the environmental temperature. Environmental temperature information indicating the environmental temperature is stored in advance in the memory unit 82. In calculating the wire temperature, the environmental temperature is considered to be a constant value.

[0092] The wire current value, the temperature difference to be calculated, the preceding temperature difference, and the environmental temperature are written as Iw, ΔTw, ΔTp, and Ta, respectively, for the wire W. The control unit 83 calculates the temperature difference ΔTw by substituting the preceding temperature difference ΔTp, the wire current value Iw, and the environmental temperature Ta into the following formulas [1] and [2]. ΔTw=ΔTp·exp(-Δt / τr)+Rth·Rw ·Iw 2 (1-exp(-Δt / τr)) [1] Rw=Ro·(1+κ·(Ta+ΔTp-To)···[2]

[0093] The variables and constants used in equations [1] and [2] are explained below. In the explanation of the variables and constants, the units of the variables or constants are also shown. The unit of the wire current value Iw is amperes. The unit of the temperature difference ΔTw, the preceding temperature difference ΔTp, and the environmental temperature Ta is degrees. Rw is the wire resistance value (Ω) of the wire W. Rth is the wire thermal resistance value (°C / W) of the wire W. Δt is the period (s) at which the control unit 83 acquires current value information. τr is the wire heat dissipation time constant (s) of the wire W. To is a predetermined temperature (°C). Ro is the wire resistance value (Ω) at temperature To. κ is the wire resistance temperature coefficient ( / °C) of the wire W.

[0094] The temperature difference ΔTw, the preceding temperature difference ΔTp, the wire current value Iw, and the environmental temperature Ta are variables, while the period Δt, the wire heat dissipation time constant τr, the wire thermal resistance Rth, the wire resistance Ro, the wire resistance temperature coefficient κ, and the temperature To are preset constants.

[0095] The value of the first term in equation [1] decreases as the period Δt becomes longer, so the first term in equation [1] represents the heat dissipation from the wire W. The value of the second term in equation [1] increases as the period Δt becomes longer, so the second term in equation [1] represents the heat generation from the wire W. The value of the second term is larger as the wire current value Iw is larger.

[0096] The control unit 83 adds the calculated temperature difference ΔTw to the environmental temperature Ta to calculate the wire temperature of the wire W. In the calculation of the temperature difference ΔTw of the wire W that is first performed by the control unit 83 after the microcomputer 22 is started, the wire temperature of the wire W is assumed to match the environmental temperature Ta, and the preceding temperature difference ΔTp is regarded as zero.

[0097] <Electric wire protection treatment> 12 is a flowchart showing the procedure of the electric wire protection process. The control unit 83 periodically executes the electric wire protection process. The memory unit 82 stores an antecedent temperature difference calculated in advance by the control unit 83. The antecedent temperature difference stored in the memory unit 82 is changed by the control unit 83.

[0098] In the wire protection process, the control unit 83 first acquires current value information from the A / D conversion unit 81 (step S11). After executing step S11, the control unit 83 reads out the preceding temperature difference from the storage unit 82 (step S12). Next, the control unit 83 calculates the temperature difference between the wire temperature of the wire W and the environmental temperature by substituting the wire current value indicated by the current value information acquired in step S11, the preceding temperature difference read out in step S12, and the environmental temperature indicated by the environmental temperature information stored in the storage unit 82 into equations [1] and [2] (step S13).

[0099] Next, the control unit 83 changes the preceding temperature difference stored in the memory unit 82 to the temperature difference calculated in step S13 (step S14). The changed preceding temperature difference is used in calculating the next temperature difference. After executing step S14, the control unit 83 calculates the wire temperature by adding the temperature difference calculated in step S13 to the environmental temperature indicated by the environmental temperature information stored in the memory unit 82 (step S15).

[0100] Next, the control unit 83 determines whether the wire temperature calculated in step S15 is equal to or higher than the temperature threshold value (step S16). When the control unit 83 determines that the calculated wire temperature is equal to or higher than the temperature threshold value (S16: YES), it instructs the output unit 80 to switch the semiconductor switch 30 to OFF (step S17). When the control unit 83 executes step S17 in a case where an ON fault has not occurred in the semiconductor switch 30, the drive circuit 31 switches the semiconductor switch 30 to OFF. This stops the flow of the wire current and reduces the wire temperature.

[0101] After executing step S17, the control unit 83 changes the value of the prohibition flag to 1 (step S18). This prohibits the semiconductor switch 30 from being switched on. If the control unit 83 determines that the wire temperature is lower than the temperature threshold value (S16: NO), or after executing step S18, the control unit 83 ends the wire protection process. When the next cycle arrives, the control unit 83 executes the wire protection process again.

[0102] As described above, the control unit 83 repeatedly calculates the wire temperature based on the wire current value. When the wire temperature reaches or exceeds the temperature threshold, the control unit 83 instructs the output unit 80 to switch the semiconductor switch 30 off and prohibits the semiconductor switch 30 from being switched on. When the semiconductor switch 30 is switched off, the wire temperature drops. The wire temperature when smoke is emitted from the wire W is referred to as the smoke temperature. The temperature threshold is lower than the smoke temperature. Therefore, the wire W is protected from smoke emission.

[0103] When the control unit 83 changes the value of the prohibition flag to 1, the control unit 83 may execute a cancellation process to return the value of the prohibition flag to 0. When the value of the prohibition flag is 1, the control unit 83 periodically executes the cancellation process. In the cancellation process, the control unit 83 also calculates the temperature difference between the electric wire temperature and the environmental temperature. For example, the control unit 83 determines whether the calculated temperature difference is equal to or less than a predetermined value. When the control unit 83 determines that the calculated temperature difference is equal to or less than the predetermined value, it changes the value of the prohibition flag from 1 to 0. The predetermined value is 0°C, 5°C, or the like.

[0104] <Timing of meltdown, cutoff and smoke generation> FIG. 13 is an explanatory diagram of the timing relating to melting, interruption, and smoking. FIG. 13 shows the interruption characteristics of the semiconductor switch 30, the melting characteristics of the fuse 20, and the smoking characteristics of the wire W. For these characteristics, the vertical axis shows the wire current value, and the horizontal axis shows the period, i.e., the length of time. Is indicates an arbitrary wire current value. T1 indicates the period corresponding to Is in the interruption characteristics. T2 indicates the period corresponding to Is in the melting characteristics. T3 indicates the period corresponding to Is in the smoking characteristics.

[0105] The interruption characteristic indicates the timing at which the drive circuit 31 switches off the semiconductor switch 30 because the wire temperature calculated by the control unit 83 has risen to a temperature equal to or higher than the temperature threshold. When the period during which the wire current with the wire current value Is continues to flow reaches T1, the drive circuit 31 switches off the semiconductor switch 30. The smaller the wire current value Is, the longer the period T1.

[0106] The fusing characteristic indicates the timing at which the fusing portion 42 of the fuse 20 melts. When the period during which the wire current with the wire current value Is continues to flow reaches T2, the fuse temperature reaches the melting temperature and the fuse 20 melts. As described above, when the fuse temperature reaches the melting temperature, the wire temperature reaches the reference temperature. The smaller the wire current value Is, the longer the period T2.

[0107] When a fuse with a rated current value of 20 A is used as fuse 20, fusing portion 42 of fuse 20 melts at the following timing, for example: When a current with a current value of 27 A continues to flow through fuse 20 for 60 seconds, fusing portion 42 of fuse 20 melts; When a current with a current value of 40 A continues to flow through fuse 20 for 1.5 seconds, fuse 20 melts.

[0108] The smoke generation characteristics indicate the timing at which smoke is generated from the wire W. When the period during which a current with a wire current value Is continues to flow through the wire W reaches T3, the wire temperature reaches the smoke generation temperature and smoke is generated from the wire W. The smaller the wire current value Is, the longer the period T3.

[0109] As shown in FIG. 13, for any wire current value Is, the period T3 is longer than the periods T1 and T2. This is because the smoke temperature of the wire W is Electric wire W This means that the temperature is higher than the reference temperature and the temperature threshold value of the wire W. As described above, the reference temperature is the wire temperature when the fuse temperature is the melting temperature. Since the smoke-generating temperature is higher than the reference temperature and the temperature threshold value, the semiconductor switch 30 is switched off or the fuse 20 is melted before the wire temperature reaches the smoke-generating temperature. Therefore, the wire W is protected from smoke generation.

[0110] Moreover, for any electric wire current value Is, the period T2 is longer than the period T1. The fact that the period T2 is longer than the period T1 means that Electric wire W This means that the reference temperature of the fuse 20 exceeds the temperature threshold of the wire temperature. When the semiconductor switch 30 is on, the wire temperature reaches a temperature equal to or higher than the temperature threshold before the fusing portion 42 of the fuse 20 melts, unless an on-failure has occurred in the semiconductor switch 30. When the wire temperature reaches a temperature equal to or higher than the temperature threshold, the drive circuit 31 switches the semiconductor switch 30 off. Therefore, unless an on-failure has occurred in the semiconductor switch 30, the fusing portion 42 of the fuse 20 will not melt. If an on-failure has occurred in the semiconductor switch 30, the fuse 20 melts before the wire temperature reaches the smoke-producing temperature.

[0111] (Embodiment 2) In the first embodiment, in the current path of the electric wire current, the fuse 20 is disposed upstream of the semiconductor switch 30. However, the location where the fuse 20 is disposed is not limited to the upstream of the semiconductor switch 30. The following describes the differences between embodiment 2 and embodiment 1. Except for the configuration described below, other configurations are common to embodiment 1. For this reason, components common to embodiment 1 are given the same reference numerals as embodiment 1, and descriptions of those components are omitted.

[0112] <Power supply system 1 configuration> 14 is a block diagram showing a configuration of a main part of a power supply system 1 in a second embodiment. In the second embodiment, the positive electrode of the DC power supply 11 is connected to the drain of the semiconductor switch 30. The source of the semiconductor switch 30 is connected to one terminal 41 of the fuse 20. The other terminal 41 of the fuse 20 is connected to one end of the electric wire W. When the semiconductor switch 30 is on, the electric wire current flows from the positive electrode of the DC power supply 11 through the semiconductor switch 30, the fuse 20, the electric wire W, and the load 12 in this order. In the current path of the electric wire current, the fuse 20 is arranged downstream of the semiconductor switch 30. In the current path, the electric wire W is arranged downstream of the fuse 20.

[0113] The power supply control device 10 in the second embodiment achieves the same effects as the power supply control device 10 in the first embodiment.

[0114] (Embodiment 3) In the second embodiment, the method by which the current detection unit 32 generates analog current value information is not limited to the method using the current drawn from the drain of the semiconductor switch 30. The following describes the differences between embodiment 3 and embodiment 2. Configurations other than those described below are common to embodiment 2. For this reason, components common to embodiment 2 are given the same reference numerals as embodiment 2, and descriptions of those components are omitted.

[0115] <Power supply system 1 configuration> 15 is a block diagram showing a configuration of a main part of a power supply system 1 in the third embodiment. Comparing the second and third embodiments, the configuration of the switch device 21 is different. The switch device 21 in the third embodiment has a shunt resistor 33 in addition to a semiconductor switch 30, a drive circuit 31, and a current detection unit 32. The shunt resistor 33 is connected between the source of the semiconductor switch 30 and a terminal 41 of the fuse 20 arranged on the upstream side. The current detection unit 32 is connected to one end and the other end of the shunt resistor 33, respectively, instead of the drain of the semiconductor switch 30.

[0116] When the semiconductor switch 30 is on, the wire current flows from the positive electrode of the DC power supply 11 through the semiconductor switch 30, the shunt resistor 33, the fuse 20, the wire W, and the load 12 in this order. The current detection unit 32 detects a voltage value between both ends of the shunt resistor 33. The voltage value between both ends of the shunt resistor 33 is expressed as (wire current value)·(resistance value of the shunt resistor 33). "·" indicates a product. The resistance value of the shunt resistor 33 is a constant value. Therefore, the voltage value between both ends of the shunt resistor 33 indicates the wire current value. The current detection unit 32 generates analog current value information indicating the wire current value based on the voltage value between both ends of the shunt resistor 33. The current detection unit 32 outputs the analog current value information to the A / D conversion unit 81 of the microcomputer 22 and the drive circuit 31, as in the second embodiment.

[0117] The power supply control device 10 in the third embodiment achieves the same effects as the power supply control device 10 in the second embodiment. The switch 21 of the power supply control device 10 in the first embodiment may be configured similarly to that in the third embodiment. The switch 21 in the third embodiment has a different configuration from that of the IPD.

[0118] (Embodiment 4) In the third embodiment, the voltage value detected by the current detection unit 32 is not limited to the voltage value between both ends of the shunt resistor 33 . The following describes the differences between the fourth embodiment and the third embodiment. Except for the configuration described below, the other configurations are common to the third embodiment. Therefore, the same reference numerals as those in the third embodiment are used for the components common to the third embodiment, and the description of those components is omitted.

[0119] <Power supply system 1 configuration> 16 is a block diagram showing a configuration of a main part of a power supply system 1 in a fourth embodiment. When comparing the third and fourth embodiments, the configuration of a switch 21 included in a power supply control device 10 is different. The switch 21 in the fourth embodiment has a semiconductor switch 30, a drive circuit 31, and a current detection unit 32, similar to the third embodiment. The switch 21 in the fourth embodiment does not have a shunt resistor 33. The current detection unit 32 is connected to two terminals 41 of the fuse 20, respectively.

[0120] As described in the description of the first embodiment, in the fuse 20, a current flows through the terminal 41, the fusion portion 42, and the terminal 41 in this order. The fusion portion 42 has a resistance component. A voltage value across the fusion portion 42 is referred to as a voltage value across both ends. The current detection portion 32 detects the voltage value across the fusion portion 42. The fuse 20 also functions as the shunt resistor 33 in the third embodiment. The voltage value across the fusion portion 42 is expressed by (wire current value)·(resistance value of the fusion portion 42). Therefore, the voltage value across the fusion portion 42 indicates the wire current value. The current detection portion 32 generates analog current value information indicating the wire current value based on the voltage value across the fusion portion 42. The current detection portion 32 outputs the analog current value information to the A / D conversion portion 81 of the microcomputer 22 and the drive circuit 31, as in the third embodiment.

[0121] The larger the wire current value, the higher the voltage value across the fusing portion 42. The voltage value across the fusing portion 42 when the wire current value is the current threshold value is referred to as the predetermined voltage value. When the voltage value across the fusing portion 42 is less than the predetermined voltage value, the wire current value is less than the current threshold value. When the voltage value across the fusing portion 42 is equal to or greater than the predetermined voltage value, the wire current value is equal to or greater than the current threshold value.

[0122] Therefore, when the voltage value across the fusing portion 42 is less than the predetermined voltage value, the drive circuit 31 switches the semiconductor switch 30 on or off according to the output voltage of the output unit 80 of the microcomputer 22, similar to the second embodiment, i.e., the first embodiment. When the voltage value across the fusing portion 42 becomes equal to or greater than the predetermined voltage value, the drive circuit 31 switches the semiconductor switch 30 off regardless of the output voltage of the output unit 80. This prevents an excessive current from flowing through the electric wire. After switching the semiconductor switch 30 off regardless of the output voltage of the microcomputer 22, the drive circuit 31 maintains the semiconductor switch 30 off until a predetermined condition is satisfied, similar to the second embodiment, i.e., the first embodiment.

[0123] In the fourth embodiment, the wire current value indicated by the current value information is a value based on the voltage value across the fusing portion 42. Therefore, in step S13 of the wire protection process, the control unit 83 calculates the temperature difference based on the voltage value across the fusing portion 42. In step S15 of the wire protection process, the control unit 83 calculates the wire temperature based on the temperature difference calculated in step S13. As described in the description of the first embodiment, the control unit 83 periodically executes the wire protection process. As a result, the control unit 83 repeatedly calculates the wire temperature based on the voltage value across the fusing portion 42.

[0124] The control unit 83 executes step S17 when the calculated electric wire temperature is equal to or higher than the temperature threshold value. When the control unit 83 executes step S17 in a case where an ON failure has not occurred in the semiconductor switch 30, the drive circuit 31 switches the semiconductor switch 30 off. The power supply control device 10 in the fourth embodiment achieves the same effects as the power supply control device 10 in the second embodiment. Note that the switch device 21 in the fourth embodiment has a different configuration from that of the IPD.

[0125] (Embodiment 5) In the first embodiment, the microcomputer 22 is included in the power supply control device 10. However, the power supply control device 10 may have a configuration in which the microcomputer 22 is not included. The following describes the differences between embodiment 5 and embodiment 1. Except for the configuration described below, other configurations are common to embodiment 1. For this reason, components common to embodiment 1 are given the same reference numerals as embodiment 1, and descriptions of those components are omitted.

[0126] <Power supply system 1 configuration> 17 is a block diagram showing a configuration of a main part of a power supply system 1 according to the fifth embodiment. As in the first embodiment, the power supply system 1 according to the fifth embodiment includes a power supply control device 10, a DC power supply 11, and a load 12. The power supply system 1 according to the fifth embodiment further includes an ECU (Electronic Control Unit) 13. In the fifth embodiment, a microcomputer 22 is not included in the power supply control device 10, but is included in the ECU 13. The connections of the microcomputer 22 are similar to those in the first embodiment.

[0127] The power supply control device 10 and the ECU 13 in the fifth embodiment achieve the same effects as those achieved by the power supply control device 10 in the first embodiment. Note that the power supply system 1 in each of the first to fourth embodiments may include an ECU 13. In this case, similar to the fifth embodiment, the microcomputer 22 is not included in the power supply control device 10 but is included in the ECU 13.

[0128] <Modification> In the first to fifth embodiments, the number of circuits including the fuse 20, the switch 21, the electric wire W, and the load 12 is not limited to one, and may be two or more. When the number of circuits is two or more, and the semiconductor switches 30 of all the switch devices 21 are on, the current output from the positive electrode of the DC power supply 11 is divided into multiple currents. Each of the multiple currents is input to multiple switch devices 21. In each circuit, the current flows through the fuse 20, the semiconductor switch 30, and the electric wire W.

[0129] Each of the multiple switches 21 outputs current information indicating a wire current value to the microcomputer 22. The control unit 83 of the microcomputer 22 executes a power supply control process and a wire protection process for each of the multiple circuits.

[0130] In the first embodiment, the number of terminals 41 of the fuse 20 is not limited to two, and may be three or more. For example, when the fuse 20 has three terminals 41, the three terminals 41 are arranged in a row in the left-right direction with the plate surfaces aligned. One fusing portion 42 is connected to the left terminal 41 and the central terminal 41. Another fusing portion 42 is connected to the central terminal 41 and the right terminal 41. The positive electrode of the DC power supply 11 is connected to the central terminal 41. When the fuse 20 has three terminals 41, the power supply system 1 has two loads 12. Two electric wires W are connected to each of the two loads 12. The power supply control device 10 has two semiconductor switches 30 and two drive circuits 31.

[0131] The drain, source and gate of one semiconductor switch 30 are connected to the left terminal 41 of the fuse 20, one end of one electric wire W and one drive circuit 31. The other end of the electric wire W is connected to one end of one load 12. The drain, source and gate of the other semiconductor switch 30 are connected to the right terminal 41 of the fuse 20, one end of the other electric wire W and the other drive circuit 31. The other end of the electric wire W is connected to one end of the other load 12. The other ends of the two loads 12 are grounded.

[0132] When one semiconductor switch 30 is on, a current flows from the positive electrode of the DC power supply 11 to one fusion portion 42 of the fuse 20, one semiconductor switch 30, one electric wire W, and one load 12 in this order. When the other semiconductor switch 30 is on, a current flows from the positive electrode of the DC power supply 11 to the other fusion portion 42 of the fuse 20, the other semiconductor switch 30, the other electric wire W, and the other load 12 in this order. The microcomputer 22 outputs a high-level voltage or a low-level voltage to each of the two drive circuits 31. The two drive circuits 31 each switch the two semiconductor switches 30 on or off according to the output voltage of the microcomputer 22. This controls the power supply to the two loads 12 separately. The two drive circuits 31 each switch the two semiconductor switches 30 off based on the electric wire current values ​​of the two electric wires W. The microcomputer 22 switches the voltages output to the two drive circuits 31 to low level voltages in accordance with the wire temperatures of the two wires W, respectively.

[0133] In the first to fifth embodiments, the semiconductor switch 30 is not limited to an N-channel FET. The semiconductor switch 30 may be a P-channel FET or a bipolar transistor. In the third and fourth embodiments, the fuse 20 may be disposed between the positive electrode of the DC power supply 11 and the drain of the semiconductor switch 30, as in the first embodiment.

[0134] In the first to fifth embodiments, the wire temperature of the wire W may be detected, for example, by using a sensor. In this case, the control unit 83 of the microcomputer 22 does not need to calculate the wire temperature. In the wire protection process, when the wire temperature is equal to or higher than the temperature threshold, the control unit 83 instructs the output unit 80 to switch off the semiconductor switch 30 and changes the value of the prohibition flag to 1.

[0135] The disclosed embodiments 1 to 5 are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0136] 1 Power System 10 Power supply control device 11 DC power supply 12 Load 20. Fuse 21 Switch 22 Microcomputer 30 Semiconductor Switch 31 Drive circuit (switching circuit) 32 Current detection section 33 Shunt Resistor 40 Housing 40a opening 41 Terminal 42 Melting point 50 Metal objects 51 Terminal plating 61 1st plate part 62 2nd plate part 70 Insulating Substrate 70a through hole 71 Substrate plating 72 Wiring Pattern 73 Resist 80 Output section 81 A / D conversion section 82 Memory section 83 Control section (processing section) 84 Internal Bus A storage medium B. Circuit board C Vehicle H Solder P Computer Program

Claims

1. A power supply control device that controls power supply through an electric wire, A fuse and a semiconductor switch are disposed in a current path of a wire current flowing through the wire; a circuit board on which the fuse and semiconductor switch are mounted; A processing unit for executing processing; Equipped with The fuse is a plurality of terminals connected to the circuit board by soldering; a fusing portion connected between two terminals among the plurality of terminals; having Two terminals among the plurality of terminals are disposed on the current path; the fusing portion is melted in response to a temperature of the fusing portion, The processing unit instructs the semiconductor switch to be switched off in response to a wire temperature of the wire, A switching circuit is provided for switching the semiconductor switch on or off. The switching circuit switches off the semiconductor switch regardless of the output voltage of the processing unit when a voltage value across the fusion portion of the fuse reaches a predetermined voltage value or more. Power supply control device.

2. The processing unit instructs the semiconductor switch to be switched off when the electric wire temperature becomes equal to or higher than a temperature threshold value, When the semiconductor switch is on, the temperature of the electric wire becomes equal to or higher than the temperature threshold value before the fusing portion is blown. The power supply control device according to claim 1 .

3. The fuse has a housing that covers a part of the plurality of terminals and the fusing portion, The housing has a heat resistance of 300 degrees or more. The power supply control device according to claim 1 or 2.

4. The circuit board includes: An insulating substrate; A plurality of through holes penetrating the insulating substrate; a plurality of substrate platings covering the insulating substrate; having The plurality of terminals of the fuse are inserted into the plurality of through holes and are connected to the plurality of board platings of the circuit board by the solder. The power supply control device according to any one of claims 1 to 3.

5. Each of the plurality of terminals is A metal body; a tin terminal plating covering the surface of the metal body; The power supply control device according to any one of claims 1 to 4, further comprising:

6. The processing unit repeatedly calculates the wire temperature based on a voltage value between both ends of the melting portion of the fuse. The power supply control device according to any one of claims 1 to 5.

7. The fuse has a housing that covers a part of the plurality of terminals and the fusing portion, Each of the plurality of terminals is a first plate portion having a long plate shape, a portion of which is covered by the housing; a second plate portion connected to the first plate portion; having For each of the plurality of terminals, one end of the first plate portion protrudes from a common surface of the housing, The second plate portion protrudes from a part of a tip surface of the first plate portion protruding from the housing, the circuit board has a plurality of through holes; the second plate portion of each of the plurality of terminals is inserted into the plurality of through holes, The first plate portion of each of the plurality of terminals contacts the circuit board. The power supply control device according to any one of claims 1 to 6.

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