JP2014053131A - Intelligent fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intelligent fuse which can form current paths which are actually different at a normal time and at a time of fault current cut-off.SOLUTION: An intelligent fuse has a first current path and a second current path which form at least two parallel current paths equal in resistance value. In the first current path, a first cut-off point composed of a fusing part and a cut-off part having a first time for maintaining arc, placed across the fusing part, and a second cut-off point composed of a fusing part and a cut-off part having a second time for maintaining arc longer than the first time for maintaining arc, placed across the fusing part, are placed by turns via a joint part. In the second current path, the second cut-off point is placed opposite the first cut-off point and the first cut-off point is placed opposite the second cut-off point. Between the joint part of the first current path and the joint part of the second current path, a bridge cut-off point is placed. The first cut-off point is divided into a plurality of divided cut-off points serially placed.

Description

  The present invention forms at least two parallel first and second current paths having the same resistance value, and the first and second current paths have first arcing points having different arc maintenance characteristics. And an intelligent fuse in which the second breaking points are alternately arranged via the connecting portions and arranged so as not to face each other in the first current path and the second current path.

Inverter devices for vehicles and other industries use semiconductor switching devices with high rated current and high voltage, and voltage-controlled semiconductor elements such as insulated gate bipolar transistors and power field effect transistors are used as the semiconductor switching devices. Has been.
In such a semiconductor switching device, a protective fuse is used to protect the voltage-controlled semiconductor element.

Conventionally, the fuse element of the fusible body is blown entirely or partially by the fault current as the protective fuse, but the current path does not change during normal or when the fault current is interrupted.
On the other hand, as described in Patent Document 1, an intelligent fuse is proposed in which the current path is changed between a normal time and an accident current interruption.

  This intelligent fuse is composed of a plurality of series break points consisting of fusing parts and cut-off parts that are simultaneously ignited in substantially the same shape, and a plurality of bridge break points that have the same or slightly longer fusing time. It has a melted part connected in series by a breakpoint and connected in parallel by each bridge breakpoint and a plurality of heat dissipating parts whose film pressure is thicker than the breaker, and the breaker maintains different arcs between the series breakpoints in parallel. The configuration has voltage characteristics.

JP-A-9-330644

  By the way, in the conventional example described in Patent Document 1, since the arc maintaining voltage characteristics of the interrupting portion are formed in different shapes, the arc generated at the interrupting point having a high arc maintaining voltage melts the fusing portion. The arc column is quickly extended, but immediately reaches a thick heat dissipation portion and stops its extension. However, the arc generated at the break point where the arc maintenance voltage is low does not sufficiently extend the arc column even if the fusing part is melted, and continues to discharge even if it reaches a thick heat radiation part. Therefore, the fault current surely moves to the side of the series breakpoint that continues to fire at a lower arc voltage as the arc voltage rises, and the meandering through each bridging breakpoint surely increases the arc voltage. The accident current is quickly suppressed.

However, in the conventional example described in Patent Document 1, the path of the fault current is meandered by forming the interrupting points having different arc maintenance voltages by changing the shape of the interrupting part. However, there is an unsolved problem that even if the interrupting points have different shapes and the interrupting points having different arc maintenance voltages are formed, the fault current cannot form a current path through the bridging interrupting unit.
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and provides an intelligent fuse capable of reliably forming different current paths at the normal time and when an accident current is interrupted. The purpose is that.

  In order to achieve the above object, a first aspect of an intelligent fuse according to the present invention includes a first current path and a second current path that form at least two parallel current paths having equal resistance values. Of these two current paths, the first current path includes a first cut-off point configured by a fusing part and a cut-off part having a first arc maintaining time across the fusing part, and the fusing part And second interruption points composed of interruption parts having a second arc maintenance time longer than the first arc maintenance time opposite to each other with the fusing part interposed therebetween, are arranged alternately via the connection parts, In the second current path, a second cutoff point is arranged at a position facing the first cutoff point, and a first cutoff point is arranged at a position facing the second cutoff point. Further, a bridging break point is disposed between the first current path connecting portion and the second current path connecting portion, and the first break point is divided into a plurality of divided break points arranged in series. ing.

According to a second aspect of the intelligent fuse of the present invention, the second breaking point is divided into a plurality of divided breaking points arranged in series, and the number of divided breaking points of the first breaking point is the second number. It is set more than the number of breakpoint divisions.
In the third aspect of the intelligent fuse according to the present invention, the first breaking point and the fusing portion of the breaking point have a plurality of parallel narrow portions, and the number of narrow portions of the first break point is the first. The number is set to be larger than the number of narrow portions of one cut-off point.

Moreover, the 4th aspect of the intelligent fuse which concerns on this invention WHEREIN: The width | variety of the narrow part formation area in the fusing part of the 1st interruption | blocking point is the bridge | crosslinking with the width | variety of the narrow part formation area in the fusing part of the 2nd interruption | blocking point. The fifth aspect of the intelligent fuse according to the present invention is the maximum current density of the first break point and the second break point. Are set equal.
According to a sixth aspect of the intelligent fuse of the present invention, the first current path and the second current path are formed of a conductive thin film pattern formed on an insulating substrate, and the first interrupting section, the first current path, The thickness of 2 interruption | blocking parts and the bridge | crossing interruption | blocking part is set thinner than the thickness of a connection part.

  According to the present invention, since the first break point is divided into a plurality of divided break points, arc discharge is generated individually at the divided break points, and the conductance of the first current path is reduced, The arc maintenance time of the second break point can be set longer than the arc maintenance time of the first break point in one current path, and the arc is reliably transferred from the first break point to the second break point having a low arc voltage. be able to. As a result, it is possible to reliably form an accident current flow path that passes through the bridge interruption point, and to quickly suppress the accident current.

It is a schematic block diagram which shows the intelligent fuse of this invention, Comprising: (a) is a top view, (b) is AA sectional view taken on the line AA. It is a figure which shows the electric current change of FIG. 1, Comprising: (a) is a top view which shows an arc generation state, (b) is a top view which shows a commutation state. It is a circuit diagram which shows the interruption | blocking test circuit. It is a figure which shows the intelligent fuse corresponding to a prior art example, (a) is a schematic top view, (b) A schematic top view which shows the arc generation condition, (c) is a schematic plane which shows the state which produced the commutation. FIG. It is a figure which shows the test result of this invention and a prior art example. It is a characteristic diagram which shows the current waveform and voltage waveform of the interruption | blocking test result of the intelligent fuse of this invention. It is a characteristic diagram which shows the current waveform and voltage waveform of the interruption | blocking test result of a prior art example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are schematic configuration diagrams showing an intelligent fuse of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA in FIG.
In the figure, 1 is an intelligent fuse. This intelligent fuse 1 is formed by forming a conductive thin film such as copper, silver or aluminum on an insulating substrate 2 made of ceramic or the like, and etching this conductive thin film. Thus, the conductive thin film pattern 4 is formed. The insulating substrate 2 is formed in a rectangular shape having a length of 40 mm, a width of 10 mm, and a thickness of 1 mm. The conductive thin film pattern 4 is formed by first forming, for example, copper of about 60 μm by vapor deposition or the like to form the thin film portion 5, patterning the thin film portion by etching, and then removing the side 60 μm at a position excluding the patterning portion using the mask. The thick film portion 6 is formed by laminating a certain amount of copper.

Here, in the conductive thin film pattern 4, the left side is formed as the first current path 11, the right side is formed as the second current path 12, and both the current paths 11 and 12 are parallel to each other and have the same resistance value. Is formed.
The first current path 11 has a first breaking point A1 having a first arc maintenance time constituted by the thin film portion 5, and a second longer than the first arc maintenance time similarly constituted by the thin film portion 5. Are formed in series via a connecting portion C constituted by the thick film portion 6 in that order. In addition, a connecting portion C composed of the thick film portion 6 is also formed outside the first blocking point A1 and outside the second blocking point B2.

  The second current path 12 has a second break point B1 having a second arc maintenance time constituted by the thin film portion 5 and a first arc having a first arc maintenance time similarly constituted by the thin film portion 5. Are connected directly to each other through a connecting part C constituted by the thick film part 6 in that order. In addition, a connecting portion C composed of the thick film portion 6 is also formed outside the second blocking point B1 and outside the first blocking point A2.

  Here, as shown in FIG. 1, each of the first cut-off points A1 and A2 is composed of divided cut-off points a1 and a2 divided into two, and a thick film portion is formed between the divided cut-off points a1 and a2. 6 is formed. And each division | segmentation interruption | blocking point a1 and a2 each has a pair of strip | belt-shaped interruption | blocking parts which opposes on both sides of this fusing part a3 which formed the circular hole at predetermined intervals, for example, formed four narrow parts, and this fusing part a3 a4.

As shown in FIG. 1, each of the second blocking points B1 and B2 includes a fusing part b1 in which a circular hole is formed to form, for example, two narrow parts, and a pair of belt-like members facing each other across the fusing part b1. It is comprised with the interruption | blocking part b2.
Furthermore, at the connection part C1 sandwiched between the first cutoff point A1 and the second cutoff point B2 of the first current path 11, and at the second cutoff point B1 and the first cutoff point A2 of the second current path 12. A bridge blocking point D is formed between the connecting portion C2 to be sandwiched. As shown in FIG. 1, the bridging cut-off point D includes a fusing part d1 having a semicircular hole and having, for example, one narrow part, and a pair of band-like cut-off parts d2 facing each other across the fusing part d1. It consists of and.

Here, the resistance values of the two blown portions a3 at the first cut-off points A1 and A2 and the blown portions b1 at the second cut-off points B1 and B2, that is, the resistances of the narrow portions are set to be equal. For this reason, the resistance value of the fusing part a3 of the divided interruption points a1 and a2 of the first interruption points A1 and A2 is set to half the resistance value of the fusing part b1 of the second interruption point B1PB2.
The width La of the two divided fusing points a1 and a2 of the first cut-off points A1 and A2 is equal to the width Lb of the fusing part b1 of the second cut-off points B1 and B2 and the fusing part d1 of the bridging cut-off point D. It is set to be larger than the value obtained by adding the width Ld (La> Lb + Ld).

  Further, since the number of cutoff points of the first cutoff points A1, A2 and the second cutoff points B1, B2 is 2: 1, the fusing parts a1, a2, and b1 of the respective cutoff points A1, A2 and B1, B2 The current density at the position of the minimum cross-sectional area is set to be equal in the narrow portion. Since the magnitude of the current flowing per narrow portion in the fusing part b1 of the second breaking points B1 and B2 is twice that of the divided breaking points a1 and a2 of the first breaking points A1 and A2, the second The minimum cross-sectional area of the narrow portion in the fusing part b1 of the interruption points B1 and B2 was set to be twice the divided interruption points a1 and a2 of the first interruption points A1 and A2. At this time, by increasing the radius of curvature of the narrow portion of the second cutoff points B1 and B2, the resistance values of the first cutoff points A1 and A2 and the second cutoff points B1 and B2 are made equal.

Next, the operation of the above embodiment will be described.
Now, semiconductor switching including a voltage-controlled semiconductor element including the rear end side 1a of the intelligent fuse 1 connected to a power source of 300A at 120V and the front side 1b with an insulated gate bipolar transistor and a power field effect transistor to be protected Connect to a device load.
In this state, when the power source is turned on and normal current is supplied to the load via the intelligent fuse 1, the first current path 11 and the second current path 12 are set to the same resistance value. 11 and 12, an equal current flows as shown in FIG.

  In this state, when a ground fault, a short circuit, or the like occurs on the load side and an accident current of about 3000 A, for example, flows through the intelligent fuse 1, in the state where the accident current starts to flow, as shown in FIG. A fault current flows equally in the current path 11 and the second current path 12, and this fault current causes an arc at the split break points a1 and a2 of the first break points A1 and A2, and the second break point B1. , B2 also generates an arc. Although the melted portions a3 and b1 of the break points A1, A2 and B1, B2 are melted by these arcs, the fault current continues to flow through the first current path 11 and the second current path 12 through the arcs.

  At this time, since the first cut-off points A1 and A2 have two divided cut-off points a1 and a2, an arc having a short distance between the cut-off portions a4 is generated at the two divided cut-off points a1 and a2. As soon as the thick connection points c and C1 are reached and arc discharge occurs at each of the divided interruption points a1 and a2, the conductance at the first interruption point is lowered, and the arc maintenance time is shortened. The arc is extinguished as shown in FIG.

  On the other hand, at the second break points B1 and B2, the arc between the break portions b2 does not extend even if the melted portion b1 is melted, and continues to discharge even when reaching the thick connection portion C or c. At this time, since no arc is generated at the bridging break point D, the fusing part d1 is not blown. Therefore, as shown in FIG. 2 (b), the fault current is the second breaking point B1, the connecting part. Unlike the normal state, a commutation state flows in a meandering manner through C, the bridge interruption point D, the connection part C, the second interruption point B2, and the connection part C. For this reason, an arc also occurs at the bridging break point D, the melted part d1 is melted, the overall arc voltage becomes higher, and the accident current is quickly suppressed.

  Thus, in order to demonstrate the effect of this invention, the interruption | blocking test was done using the interruption | blocking test circuit shown in FIG. At this time, an intelligent fuse 100 having the same configuration as that of the conventional example shown in FIG. Here, as shown in FIG. 4A, the conventional intelligent fuse 100 has breaking points A11 and A12 having a long width in the front-rear direction and a high arc maintenance voltage, and a breaking point having a short width in the front-rear direction and a low arc maintenance voltage. The points B11 and B12 are arranged in the first current path 101 and the second current path 102 via the connecting portion C as in the above-described embodiment, and the first current path 101 and the second current path 102 are A bridge cutoff point D11 is disposed between the connecting portions C.

  In this conventional intelligent fuse 100, when an accident current flows, as shown in FIG. 4B, an arc is generated at each of the breaking points A11, A12 and B11, B12, and the arc maintaining voltage at the breaking points A11, A12. Therefore, as shown in FIG. 4C, the arc is extinguished first, and the fault current meanders through the break point B11, the bridge break point D11, and the break point 12.

On the other hand, as shown in FIG. 3, the interruption test apparatus connects a variable single-turn transformer 21 to a commercial AC power supply 20 and connects a transformer 22 to the output side of the variable single-turn transformer 21. A series circuit of a diode 23, a resistor Rc, and a capacitor C is connected to the output side of the transformer 22, and a normally open switch 24 that is opened by a resistor Rd and a plunger is connected in parallel with the capacitor C.
In addition, a series circuit of a charging device 25, a fuse box 26 and a resistor Rsh is connected to the discharge path of the capacitor C. In the fuse box 26, the intelligent fuse 1 of the present invention and the intelligent fuse 100 of the conventional example were arranged, filled with arc-extinguishing sand, and the interruption test was performed while applying a pressure of 3 MPa to the load of the case with a pressure pump.

That is, in the interruption test, first, the capacitor C is charged with the normally open switch 24 opened. When the charging of the capacitor C is completed, the input device 25 is operated to supply a current of 1900 to 3000 A corresponding to the accident current to the intelligent fuse 1 or 100 in the fuse box 26 using the current charged in the capacitor C as a short-circuit current. .
The first current path 11 of the intelligent fuse 1 (or 100) of this time (or 101) and the voltage _{V F} across the second current path 12 across the voltage _{V L} and _{V R} and the fuse box 26 (or 102) (= V _L + V _R ) was measured.

  The external appearances of the intelligent fuses 1 and 100 that have completed this interruption test are as shown in FIGS. 5 (a) and 5 (b). In the intelligent fuse 1 of the present invention, as shown in FIG. 5A, the arc-extinguishing sand is cooled at all of the first breaking points A1, A2, the second breaking points B1, B2, and the bridge breaking point D. A mass called fulgrite was confirmed. As a result, the first breakpoints A1, A2, the second breakpoints B1, B2 and the bridge breakpoint D are all blown out, and meandering through the bridge breakpoint D occurs, resulting in a commutation state. It can be determined that this is happening.

On the other hand, in the conventional intelligent fuse 100 as a comparative example, as shown in FIG. 5B, fulgurite was generated at the first cutoff points A11 and A12 and the second cutoff points B11 and B12. However, the occurrence of fulgurite was not confirmed for the bridging break point D11, and it was confirmed that the bridging break point D11 may not be melted.
Whether or not the commutation between the intelligent fuse 1 of the present invention and the intelligent fuse 100 of the conventional example has occurred is determined from the current waveform at the time of interruption and the voltage waveforms of the first current path and the second current path. Judgment can be made.

In the intelligent fuse 1 of the present invention, the current waveform and voltage waveform when the capacitor C is charged with 120V are as shown in FIGS. 6 (a) and 6 (b), when the current reaches the peak current (1900A). when you start limiting from 9 .mu.s, substantially constant voltage once voltage increase stops from the voltage V _L and the voltage V _R of the second current path 12 of the first current path 11 is increased both in the same way maintaining (about 120V), then the voltage _{V L} of the first current path 11 is decreased after 48.9Myuesu, voltage _{V R} of the second current path 12 is increased, the voltage difference between them occurs, then It was confirmed that the voltage decreased with the same voltage change.

From the change of the voltage _{V L} and _{V R,} the voltage _V F at 38.9Myuesu, which rises in the _{V L} and _{V R,} at the same time the arc in the first cut-off point A1, A2 and the second cut-off point B1, B2 are It can be judged that it has occurred. For this reason, it is considered that a parallel current path is formed by the first current path 11 and the second current path 12. At this time, it is determined that the arc current at the first break points A1 and A2 is reduced due to the difference in conductance of the current path and commutates to the second break points B1 and B2, and current starts to flow to the bridge break point D. be able to. Then, at the time of 48.9Myuesu, blown is blown part d1 of the bridge cutoff point D, it can be determined that appear as a voltage difference between the arc voltage V _L and V _R at that time.

On the other hand, in the intelligent fuse 100 of the conventional example, the current and voltage when the capacitor C is charged to 160V are 81.8 μS and the peak current (3000 A) as shown in FIGS. reached by the time you start the current limiting, voltage _V F, the arc _{V L} and _{V R} are both stand up since that first cutoff point A11, A12 and the second cutoff points B11, B12 occurs I can judge. Thereafter it is determined that the arc is not generated in the first current path 101 and the second current path 102 voltage V _L and V the voltage difference bridge cutoff point for about several volts at the maximum of _R D11 of This is consistent with the result shown in FIG.

  Thus, according to the present embodiment, the first interrupting points A1 and A2 are divided into two divided interrupting points a1 and a2, so that the resistance values of these divided interrupting points a1 and a2 are set to the second interrupting point B1. , B2 to match the resistance value, the interval between the interrupting portions a4 is shortened, the arc length increases, the arc current increases, the arc voltage increases due to the pole drop voltage at the divided interrupting points a1 and a2, and the arc maintaining time Becomes shorter than the second cutoff points B1 and B2. For this reason, arc-extinguishing arises at the division | segmentation interruption | blocking points a1 and a2, and the commutation of an accident electric current can be reliably generated in 2nd interruption | blocking point B1, B2.

Further, since the current density at the minimum cross-sectional area position of the first cutoff points A1 and A2 and the second cutoff points B1 and B2 is made equal, the split cutoff points a1 and a2 of the first cutoff points A1 and A2 The arc generation timing for generating an arc can be matched with the second cutoff points B1 and B2.
In the above embodiment, the case where there are two current paths of the intelligent fuse 1 has been described. However, the present invention is not limited to this, and three or more current paths may be formed. Further, the number of the first interception points A and the second interception points B is not limited to one, but two or more can be formed, and if there are two or more bridging breakpoints accordingly, Good.

  Furthermore, although the said embodiment demonstrated the case where the serial interruption point ratio of 1st interruption | blocking point A1, A2 and 2nd interruption | blocking point B1, B2 was set to 2: 1, it is not limited to this. The ratio of the number of series breaking points can be set to 3: 2. In short, the number of breaking points of the first breaking points A1 and A2 is set larger than the number of breaking points of the second breaking points B1 and B2, and the conductance of the current path is set. It is only necessary to make a difference.

  DESCRIPTION OF SYMBOLS 1 ... Intelligent fuse, 2 ... Insulating substrate, 4 ... Conductive thin film pattern, 11 ... 1st electric current path, 12 ... 2nd electric current path, A1, A2 ... 1st interruption | blocking point, a1, a2 ... division | segmentation interruption | blocking point , A3 ... fusing part, a4 ... blocking part, B1, B2 ... second blocking point, b1 ... fusing part, b2 ... blocking part, C ... connecting part, D ... bridging blocking point, d1 ... fusing part, d2 ... Interceptor

Claims (6)

A first current path and a second current path forming at least two parallel current paths having equal resistance values;
The first current path includes a first cut-off point configured by a fusing part and a cut-off part having a first arc maintaining time opposed to the fusing part, and the fusing part and the fusing part. Second interruption points constituted by interruption parts having a second arc maintenance time longer than the opposing first arc maintenance time are alternately arranged via connecting parts,
In the second current path, the second cutoff point is arranged at a position facing the first cutoff point, the first cutoff point is arranged at a position facing the second cutoff point,
A bridging break point is disposed between the connecting portion of the first current path and the connecting portion of the second current path;
The intelligent fuse characterized in that the first breaking point is divided into a plurality of divided breaking points arranged in series.   The second blocking point is divided into a plurality of divided blocking points arranged in series, and the number of divided blocking points of the first blocking point is set larger than the number of divisions of the second blocking point. Item 4. The intelligent fuse according to item 1.   The fusing part of the first interruption point and the second interruption point has a plurality of parallel narrow parts, and the number of narrow parts of the first interruption point is set larger than the number of narrow parts of the first interruption point. The intelligent fuse according to claim 1, wherein the intelligent fuse is provided.   The width of the narrow portion formation region at the fusing portion at the first interception point is the sum of the width of the narrow portion formation region at the fusing portion at the second interception point and the width of the narrow portion formation region at the bridge interception point. The intelligent fuse according to claim 3, wherein the intelligent fuse is set to be larger than a predetermined width.   5. The intelligent fuse according to claim 1, wherein maximum current densities of the first break point and the second break point are set to be equal to each other.   The first current path and the second current path are formed of a conductive thin film pattern formed on an insulating substrate, and the first blocking section, the second blocking section, and the bridging blocking section The intelligent fuse according to any one of claims 1 to 5, wherein the thickness is set to be thinner than the thickness of the connecting portion.

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