JP7337214B1 - power converter - Google Patents

Abstract

An object of the present invention is to obtain a power converter device in which damage to surrounding components caused by melting of a fuse part is suppressed by filling a resin member for embedding a fuse part in an optimal filling amount at low cost. [Solution] A power semiconductor element, a heat sink to which the power semiconductor element is thermally connected, a bus bar, and a case in which the bus bar is integrally formed, the bus bar is connected to the main body and the power semiconductor element. The connecting terminal has a fuse part whose cross-sectional area is smaller than the front and rear parts, the case has a fuse enclosure part surrounding the fuse part, the fuse part is exposed from the case, and the fuse part is The enclosure has a first end surface opposite to the placement surface, and has at least one notch recessed toward the outer circumference and the placement surface at the inner end of the first end surface, and has at least one notch recessed toward the outer circumference and the placement surface side, The inside of the enclosure is filled with a fuse part embedding resin member in which the fuse part is embedded from the placement surface to a position where part or all of the cutout part is buried. [Selection diagram] Figure 5

Description

The present application relates to a power converter.

In recent years, in the automobile industry, motor-driven vehicles such as hybrid vehicles and electric vehicles have been actively developed as environment-friendly vehicles. A power conversion device that drives a motor supplies high-voltage drive power to a motor drive circuit using a battery as a power source. Also, resin-encapsulated power semiconductor elements are used in power converters, and the importance of power converters as key devices in the field of power electronics is increasing.

Here, the power semiconductor element used in the power converter is resin-sealed together with other components. In such a power converter, if a power semiconductor device or an electronic component such as a smoothing capacitor forming a snubber circuit is short-circuited while power is being supplied from a battery, an excessive short-circuit current flows. For example, if the upper and lower arms of the power converter are short-circuited due to malfunction of the gate drive circuit in the control circuit, an overcurrent will flow through the power semiconductor element, causing a short-circuit failure.

If the relay that connects the battery and the motor drive circuit is connected or continued to be connected in the short-circuit state, the power converter will be damaged by the large current. Also, it is conceivable that a battery connected to the power conversion device may be damaged due to overcurrent exceeding the rating. In order to avoid such a situation, a sensor for detecting overcurrent is usually used to control the switching of the power semiconductor element at high speed to cut off the current when the overcurrent flows. However, even when a power semiconductor device has a short-circuit failure, it is desired to more reliably prevent failure modes such as the damage described above.

Specifically, for example, by inserting an overcurrent cutoff fuse between the power semiconductor element and the battery, overcurrent flowing between the power converter and the battery can be prevented. However, chip-type overcurrent interrupting fuses are expensive. Therefore, there is a need for an inexpensive overcurrent interrupting means capable of reliably interrupting an overcurrent that may flow to a battery when a short-circuit failure occurs in a power semiconductor device. As an overcurrent interrupting means, a fuse portion is provided on a part of a bus bar that supplies electric power from the battery to the power semiconductor element, and a resin member for embedding the fuse portion is filled around the fuse portion so that the fuse portion is embedded in the resin member. An embedded configuration is disclosed (see, for example, Patent Document 1).

JP 2019-161967 A

In Patent Document 1, the fuse portion is embedded in the fuse portion-embedding resin member. Since the resin member for embedding the fuse portion is embedded in the resin member for embedding and holds the melting member dispersedly, it is possible to prevent the conductive path from being maintained by the melting member after fusing, and to promptly open the conductive path. can be cut. However, since it is difficult to fill a predetermined amount of the fuse portion-embedding resin member that covers the periphery of the fuse portion, if the filling amount is small, the melted member will scatter outside from the fuse portion-embedding resin member, There was a problem of damaging the parts of In addition, if the melted material is not sufficiently dispersed inside the fuse portion-embedding resin member and the energization path in the blown portion of the fuse portion is maintained even after the fuse portion is melted, a short-circuit current may flow through the blown portion. As a result, the temperature of the fused part becomes high, and the heat is transmitted to the surrounding parts, causing damage to the surrounding parts.

Moreover, when the amount of the fuse portion-embedding resin member to be filled is larger than the predetermined amount, there is a problem that the cost is higher than expected. In order to fill the fuse portion-embedding resin member with a predetermined amount, it is necessary to manage the filling amount or the filling height. In the configuration of Patent Document 1, it is necessary to check the filling height by directly measuring the filling height, so there is a problem that inspection equipment for checking the filling height becomes expensive.

SUMMARY OF THE INVENTION Accordingly, an object of the present application is to obtain a power conversion device in which a fuse portion-embedding resin member is filled with an optimum filling amount at a low cost, and damage to surrounding components caused by melting of the fuse portion is suppressed.

The power conversion device disclosed in the present application includes a power semiconductor element, a heat sink having an arrangement surface to which the power semiconductor element is thermally connected, a bus bar for supplying power to the power semiconductor element, and and a case in which a bus bar is integrally formed, the bus bar having a main body and connection terminals extending from the main body and connected to wiring members of the power semiconductor device, the connection terminals being arranged on the arrangement surface. and has a fuse portion smaller in cross-sectional area than the front and rear portions. a fuse enclosing portion that protrudes outward and surrounds the fuse portion; the fuse portion is exposed from the case; the fuse enclosing portion is cylindrically formed to surround the fuse portion; has a first end face opposite to the fuse enclosure, and at the inner peripheral end of the first end face, at least one notch recessed toward the outer peripheral side and the arrangement surface side, and inside the fuse enclosing part In (1), the fuse portion-embedding resin member that embeds the fuse portion is filled from the arrangement surface to a position where the notch portion is partially or wholly buried.

According to the power conversion device disclosed in the present application, the connecting terminal extending from the main body of the bus bar has the fuse portion having a smaller cross-sectional area than the front and rear portions, and the case is arranged in a direction perpendicular to the arrangement surface. and a fuse enclosing portion surrounding the fuse portion, the fuse portion being exposed from the case, the fuse enclosing portion having a first end surface opposite to the arrangement surface, and extending to the inner peripheral side of the first end surface. at the end of the fuse has at least one notch recessed toward the outer peripheral side and the placement surface side; Since it is filled up to the position where part or all of the notch is buried, the height of the notch is set so that when the fuse part is melted, the melted material of the fuse part is enough inside the fuse enclosure. By setting the filling height of the fuse portion-embedding resin member so that the fuse portion-embedding resin member does not scatter to the outside, it is possible to fill the fuse portion-embedding resin member with an optimum filling amount at low cost. In addition, the melted material is sufficiently dispersed inside the fuse enclosure, and the filling height of the resin material for embedding the fuse is secured so that it does not scatter to the outside. can be suppressed.

1 is a schematic perspective view of a power converter according to Embodiment 1; FIG. 1 is a schematic perspective view of a main part of a power converter according to Embodiment 1; FIG. 1 is a perspective view showing an outline of a busbar of a power conversion device according to Embodiment 1; FIG. 1 is a plan view showing an outline of a power converter according to Embodiment 1; FIG. FIG. 5 is a cross-sectional view schematically showing the power conversion device taken along line AA in FIG. 4; 4 is a diagram for explaining the current density of the fuse portion of the power conversion device according to Embodiment 1; FIG. 1 is a diagram showing a main part of a power converter according to Embodiment 1; FIG. 1 is a diagram showing a main part of a power converter according to Embodiment 1; FIG. It is a figure explaining the principal part of the power converter device of a comparative example. FIG. 4 is a plan view showing an outline of another power conversion device according to Embodiment 1; FIG. 4 is a plan view showing an outline of another power conversion device according to Embodiment 1; FIG. 4 is a cross-sectional view showing a main part of another power conversion device according to Embodiment 1; FIG. 10 is a diagram showing a main part of a power conversion device according to Embodiment 2; FIG. 10 is a diagram showing a main part of a power conversion device according to Embodiment 3; FIG. 11 is a diagram showing a main part of a power conversion device according to Embodiment 4; FIG. 13 is a diagram showing a main part of a power conversion device according to Embodiment 5;

Power converters according to embodiments of the present application will be described below with reference to the drawings. In each figure, the same or corresponding members and parts are denoted by the same reference numerals. Also, in the illustrations between the figures, the size and scale of each corresponding component are independent of each other.

Embodiment 1.
FIG. 1 is a perspective view showing an outline of a power conversion device 1 according to Embodiment 1, in which a part of a fuse portion-embedding resin member 25 and a cylindrical portion 16a of a case 16 are removed, and FIG. 3 is a perspective view schematically showing the busbar 11 and the case 16 of the converter 1, FIG. 3 is a perspective view schematically showing the busbar 11 of the power converter 1, and FIG. A view showing the embedding resin member 25 and a part of the cylindrical portion 16a of the case 16 removed, FIG. 5 is a cross-sectional view schematically showing the power conversion device 1 cut along the AA cross-sectional position in FIG. 4, and FIG. is a diagram for explaining the current density of the fuse portion 23 of the power conversion device 1 according to Embodiment 1, FIG. 7 is a diagram showing a main part of the power conversion device, and FIG. FIG. 7B is a cross-sectional view showing the surrounding portion of the fuse portion 23 with the fuse portion-embedding resin member 25 removed, and FIG. 8(a) is a perspective view showing a portion around the fuse portion 23, and FIG. 8(b) is a sectional view showing a portion around the fuse portion 23. FIG. be. The power converter 1 is a device that converts an input current from DC to AC, vice versa, or converts an input voltage to a different voltage.

<Power converter 1>
The power conversion device 1 includes a power semiconductor element 14 , a bus bar 11 , a heat sink 13 and a case 16 . As shown in FIG. 1, the housing 12 is formed of a heat sink 13 and a case 16 in a cylindrical shape with a bottom. The housing 12 accommodates the power conversion module 10 having the power semiconductor element 14 and the bus bar 11 . The heat sink 13 has an arrangement surface 13a to which the power semiconductor element 14 is thermally connected. The busbar 11 supplies power to the power semiconductor element 14 . The case 16 is arranged on the arrangement surface 13a and integrally forms the busbar 11 . The details of each unit will be described below. In the description of each part, the “vertical direction” means the direction in which the cylindrical portion 16a of the housing 12 extends, and the “horizontal direction” means the direction in which the heat sink 13, which is the bottom of the housing 12, extends. direction. In FIG. 5, A indicates the vertical direction, and B indicates the horizontal direction.

<Power conversion module 10>
In this embodiment, the power conversion device 1 has two power conversion modules 10 . The number of power conversion modules 10 included in the power converter 1 is not limited to two. As shown in FIG. 5, the power conversion module 10 includes a plurality of wiring members 17 formed in a wiring pattern, a power semiconductor element 14 capable of switching operation, the power semiconductor element 14, and an output-side wiring member. 17b, a control terminal 19, a conductive bonding material 20, and a mold resin 21 for sealing them. The wiring member 17 may have other mounted components (not shown) such as a temperature sensor. The conductive bonding material 20 connects the positive electrode side wiring member 17a and the power semiconductor element 14, the semiconductor element wiring member 18 and the output side wiring member 17b, and the semiconductor element wiring member 18 and the power semiconductor element 14 together. Join each other.

A protruding portion 13b that vertically protrudes from the placement surface 13a is provided at a portion of the placement surface 13a of the heat sink 13 that faces the power conversion module 10 . The projecting portion 13b and the projecting portion 13b side of the power conversion module 10 are in contact with each other via the heat dissipation member 22 having electrical insulation. The power semiconductor element 14 and the heat sink 13 are electrically insulated by the heat dissipation member 22 . The heat generated by the power semiconductor element 14 is conducted to the heat sink 13 via the sheet-shaped heat dissipation member 22 . The heat sink 13 efficiently radiates the heat generated by the power semiconductor element 14 to the outside air. Thus, the power conversion module 10 is fixed to the heat sink 13 while being electrically insulated and thermally connected to the heat sink 13 .

The heat dissipation member 22 is made of a material with high thermal conductivity and high electrical insulation. The heat radiating member 22 is made of a resin such as silicon resin, epoxy resin, or urethane resin having thermal conductivity of 0.1 W/(m·K) to several tens of W/(m·K) and insulating properties. Adhesive, grease, or insulating sheet made of material. The heat dissipation member 22 can also be configured by combining a resin material with another material having low thermal resistance and insulation, such as a ceramic substrate or a metal substrate. The heat sink 13 may have an insulating layer on the surface facing the fixed portion of the power conversion module 10, and the power conversion module 10 may be fixed to the insulating layer via solder, heat dissipation grease, or the like.

The wiring member 17 is made of a metal having good electrical conductivity and high thermal conductivity, such as copper, aluminum, a copper alloy, or an aluminum alloy, in a flat plate shape. The surface of the wiring member 17 may be plated with a metal material such as Au, Ni or Sn. A large current of several amperes to several hundred amperes flows through the wiring member 17 . As shown in FIG. 1, the control terminal 19 and the end of the wiring member 17 protrude from the mold resin 21 to the outside. After protruding from the mold resin 21, the ends of the control terminals 19 and the wiring members 17 extend laterally along the placement surface 13a of the heat sink 13 while keeping a gap from the placement surface 13a of the heat sink 13, After that, it is bent and extends longitudinally away from the heat sink 13 . The control terminal 19 is a gate signal line connected to the gate terminal of the power semiconductor element 14, a sensor signal line for transmitting information such as the temperature in the power conversion module 10 to the outside, and the like. The control terminal 19 is connected to a control board (not shown) mounted on the power converter 1 . The control board controls on/off of the power semiconductor element 14 .

A connection end portion 17a1, which is a portion of the end portion of the wiring member 17a on the positive electrode side and extends in the vertical direction away from the heat sink 13, is connected to a connection terminal 11b formed on the bus bar 11, as shown in FIG. , connected by welding, soldering, or caulking. The wiring member 17 a on the positive electrode side is connected via the bus bar 11 to a power source such as a power supply device or a battery provided outside. A connection end portion 17b1, which is a portion of the end portion of the wiring member 17b on the output side that extends in the vertical direction away from the heat sink 13, is welded, soldered, or caulked to another connection terminal (not shown). etc., and is electrically connected to, for example, a rotating electric machine provided outside. A connection end portion 17c1, which is a portion of the end portion of the wiring member 17c on the negative electrode side that extends in the vertical direction away from the heat sink 13, is welded, soldered, or caulked to another connection terminal (not shown). etc., and electrically connected to the battery ground or the ground portion of the power converter 1 . The connecting end portion 17c1 of the wiring member 17c on the negative electrode side may be directly connected to the heat sink 13 by screwing or the like to electrically connect the connecting end portion 17c1 and the ground of the power converter 1 .

The power semiconductor element 14 is, for example, a power field effect transistor (power MOSFET, Power Metal Oxide Semiconductor Field Effect Transistor) or an insulated gate bipolar transistor (IGBT, Insulated Gate Bipolar Transistor). These are semiconductor devices used in power converters that drive equipment such as motors, and control rated currents of several amperes to several hundred amperes. Silicon (Si), silicon carbide (SiC), gallium nitride (GaN), or the like is used as the material of the power semiconductor element 14 .

The power semiconductor element 14 is formed in the shape of a rectangular flat chip. The power semiconductor element 14 is provided with a drain terminal as a main electrode on the surface on the side of the heat sink 13 and a source terminal as a main electrode on the surface opposite to the heat sink 13 . A gate terminal connected to the control terminal 19 is provided on the surface on which the source terminal is provided. A sensor terminal for detecting the current flowing between the main electrodes and a sensor terminal for detecting the temperature of the power semiconductor element 14 may be further provided and connected to the control terminal 19 . In this embodiment, one power semiconductor element 14 is provided in one power conversion module 10, but the number of power semiconductor elements 14 is not limited to this. Two power semiconductor elements 14 may be provided inside one power conversion module 10, and the two power semiconductor elements 14 and wiring members 17 may be joined to form upper and lower arms.

The drain terminal of the power semiconductor element 14 is connected to the electrode connection portion of the wiring member 17a on the positive electrode side by a conductive bonding material 20. As shown in FIG. The source terminal of the power semiconductor element 14 is connected to the wiring member 17b on the output side through the semiconductor element wiring member 18 . Since a large current flows through the semiconductor element wiring member 18, the semiconductor element wiring member 18 is manufactured by processing a plate material of, for example, gold, silver, copper, aluminum, a copper alloy, or an aluminum alloy. The semiconductor element wiring member 18 may be formed by wire bonding, ribbon bonding, or the like. The gate terminals and sensor terminals are connected to control terminals 19 by wire bonds made of gold, copper, aluminum, or the like, or ribbon bonds of aluminum.

In the present embodiment, the surfaces of the wiring member 17 a on the positive electrode side and the wiring member 17 b on the output side on the heat sink 13 side are exposed to the outside without being sealed with the mold resin 21 . The exposed portions of the wiring member 17 a on the positive electrode side and the wiring member 17 b on the output side are in contact with the projecting portion 13 b of the heat sink 13 via the heat radiating member 22 . The heat generated by the power semiconductor element 14 is transmitted to the heat sink 13 via the electrode connecting portion of the wiring member 17 a on the positive electrode side and the heat radiating member 22 . The surface of the wiring member 17 a on the positive electrode side facing the heat sink 13 may be covered with the mold resin 21 . At this time, the mold resin 21 covering the heat sink 13 side surface of the positive electrode side wiring member 17a has a thermal conductivity different from that of the mold resin 21 covering the power semiconductor element 14 side surface of the positive electrode side wiring member 17a. It doesn't matter if you do.

Moreover, in order to define the thickness of the heat dissipation member 22, a protrusion (not shown) may be provided on the side of the heat sink 13 of the mold resin 21 or on the side of the projecting portion 13b of the heat sink 13. FIG. By pressing a projection formed on the mold resin 21 against the heat sink 13 or the projecting portion 13b, the thickness of the heat radiating member 22 can be defined by the height of the projection. By defining the thickness of the heat radiating member 22, the insulation and heat transfer properties of the heat radiating member 22 can be managed. For example, in a low-voltage automobile using a battery of 12V, 24V, 48V, etc., the creepage distance required to secure a predetermined dielectric voltage is about 10 μm. Therefore, in the case of a low withstand voltage automobile, the thickness necessary for insulation can be reduced, so that the protrusions of the mold resin 21 can be shortened, and the power conversion device 1 can be made thin. If the heat radiating member 22 is made of a rigid material and the change in thickness is small when the heat radiating member 22 is pressed, the thickness of the heat radiating member 22 can be controlled in advance, so there is no protrusion of the mold resin 21 . I don't mind. The protrusion can control the distance between the wiring member 17 and the heat sink 13, and can control the distance between the heat sink 13 and the fuse portion 23 formed on the connection terminal 11b, which will be described later. insulation can be managed.

<Case 12>
The heat sink 13 is made of, for example, a pure metal such as aluminum, iron, or copper, or an alloy such as an aluminum alloy, an iron alloy, or a copper alloy. These materials are materials having a thermal conductivity of 20 W/(m·K) or higher. In this embodiment, the heat sink 13 is formed in a rectangular plate shape. The shape of the heat sink 13 is not limited to a rectangular flat plate shape. A plurality of flat plate-like fins 15 arranged at intervals are provided on the outer surface 13c of the heat sink 13 opposite to the placement surface 13a. The fins 15 are in contact with the outside air, and the heat sink 13 radiates heat from the fins 15 to the outside. It should be noted that the heat sink 13 may be provided with a channel through which the coolant flows.

The case 16 is made of a resin material having high insulation and thermoplasticity. Resin materials are, for example, polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyetheretherketone (PEEK). The case 16 has a portion integrally formed with the busbars 11, a cylindrical portion 16a surrounding the power conversion module 10 and the busbars 11, and a fuse enclosing portion 24, which will be described later. The case 16 is fixed to the placement surface 13a by screwing, bonding, or the like.

<Busbar 11>
As shown in FIG. 3, the busbar 11 has a main body portion 11a and a connection terminal 11b extending from the main body portion 11a and connected to a positive electrode side wiring member 17a to which the power semiconductor element 14 is connected. The connection terminal 11b has a fuse portion 23 extending along the placement surface 13a and having a smaller cross-sectional area than the front and rear portions. The bus bar 11 is made of metal such as copper, aluminum, copper alloy, or aluminum alloy, which has good electrical conductivity and high thermal conductivity. In this embodiment, bus bar 11 is formed in a plate shape. The body portion 11a of the busbar 11 is not limited to a plate shape, and may be columnar. The surface of the busbar 11 may be plated with a metal material such as Au, Ni, Sn, or the like. A large current of several amperes to several hundred amperes flows through the bus bar 11 . The number of busbars 11 is not limited to one, and a plurality of busbars 11 may be provided. One or more fuse units 23 are provided according to the configuration of the power conversion module 10 .

The fuse portion 23, which is a part of the connection terminal 11b, is a portion that functions as a fuse. In the present embodiment, the fuse portion 23 is provided in a portion extending laterally along the arrangement surface 13a of the connection terminal 11b. The fuse portion 23 is a portion of the connection terminal 11b having a smaller cross-sectional area than the portions before and after the current flow direction. That is, the fuse portion 23 has a smaller cross-sectional area than the front (upstream) and rear (downstream) portions of the fuse portion 23 in the direction of current flow. As shown in FIG. 6, when an overcurrent flows through the busbar 11, the current density of the fuse portion 23 having a smaller cross-sectional area than that of the front and rear portions increases. The arrows in FIG. 6 represent the current density. When the current density of the fuse portion 23 increases, the temperature of the fuse portion 23 rises locally compared to other locations, and the fuse portion 23 melts to cut off the overcurrent.

The fuse portion 23, which is a portion of the busbar 11, is made of metal such as copper, aluminum, copper alloy, or aluminum alloy having high electrical conductivity, similarly to the busbar 11. FIG. The fuse portion 23 may be made of a material different from that of the busbar 11, or may be made of gold or silver having high electrical conductivity. Although not limited to this, the fuse portion 23 is formed by punching a flat plate made of copper or a copper alloy having a thickness of about 0.5 mm to 1.5 mm, like the other portions of the bus bar 11. can be easily formed by The shape of the fuse portion 23 may be any shape as long as it reduces the cross-sectional area. As shown in FIG. 2, the fuse portion 23 is surrounded by the member of the case 16 in the horizontal direction without the member of the case 16 in the vertical direction.

<Fuse enclosure 24>
As shown in FIG. 4, the case 16 has a fuse enclosing portion 24 surrounding the fuse portion 23 when viewed in a direction perpendicular to the placement surface 13a. The fuse portion 23 is exposed from the case 16 . The fuse enclosing portion 24 is integrated with the portion of the case 16 integrally formed with the bus bar 11 . In the present embodiment, the shape of the inner periphery of the fuse enclosing portion 24 is rectangular when viewed in the direction perpendicular to the arrangement surface 13a, but the shape of the inner periphery is not limited to the rectangle. Inside the fuse enclosing portion 24, as shown in FIG. 8A, a fuse portion-embedding resin member 25 in which the fuse portion 23 is embedded extends from the disposition surface 13a to a part of a notch portion 26 described later or It is filled up to the position where it is completely filled. The fuse portion 23 is isolated from the outside air by the fuse portion-embedding resin member 25 . With this configuration, a short circuit between the power semiconductor element 14 and the housing 12 in the fuse portion 23 and a short circuit due to a circuit abnormality inside the power semiconductor element 14 occur, causing a large current to flow, and the fuse portion When the fuse portion 23 is fused, the melted member of the fused portion 23 can be prevented from scattering to the outside. In addition, the melted member is sufficiently dispersed inside the fuse portion-embedding resin member 25, and it is possible to prevent the maintenance of the current path in the blown portion of the fuse portion 23 after the fuse portion 23 has been blown.

A rubber material, silicone rubber, or silicone gel, for example, is used for the fuse portion-embedding resin member 25 . By using such a material for the fuse portion-embedding resin member 25, when the fuse portion 23 melts due to an overcurrent, the melted member that scatters in a plurality of spherical lumps is replaced by a soft fuse portion with a low Young's modulus. It can be embedded in the embedding resin member 25 to effectively disperse and hold the melting member inside the fuse portion embedding resin member 25 . Therefore, after the fuse portion 23 is fused, the melted member prevents the energization path of the connection terminal 11b from being maintained, and the energization path can be quickly cut off.

As the fuse-embedding resin member 25, it is desirable to use a silicone resin having an arc-extinguishing action for arc discharge that occurs when the fuse 23 is melted by an overcurrent. According to this configuration, it is possible to suppress the continuation of the current due to the arc discharge even after the fuse portion 23 is blown, and the current can be cut off immediately after the blow. Therefore, damage to the power semiconductor element 14 can be further suppressed.

As shown in FIGS. 9(a) and 9(b), if the amount of the fuse portion-embedding resin member 25 is too small, it is not possible to prevent the melted member of the melted fuse portion 23 from scattering outside. 9A and 9B are diagrams for explaining the main part of the power conversion device of the comparative example, FIG. 9A is a perspective view showing the part around the fuse part 23, and FIG. 9B is the part around the fuse part 23. It is a cross-sectional view showing the. On the other hand, if the amount of the fuse portion-embedding resin member 25 is too large, the material cost is increased and the fuse portion-embedding resin member 25 leaks out from the fuse enclosing portion 24, resulting in the fuse portion-embedding resin member 25 leaking out. Since it adheres to the parts, there may arise problems such as the possibility of part failure and current path abnormality. In order to fill the fuse enclosing portion 24 with a large amount of the fuse portion-embedding resin member 25, it is necessary to increase the height of the fuse enclosing portion 24 in the vertical direction. If the vertical height of the fuse enclosing portion 24 is increased, the size of the power converter 1 cannot be reduced. Therefore, it is required to provide the fuse enclosing portion 24 with an appropriate vertical height and to fill the fuse portion-embedding resin member 25 to an appropriate height.

<Notch 26>
The notch portion 26, which is the main part of the present application, will be described. The cutout portion 26 is provided in the fuse enclosing portion 24 to increase the accuracy of the filling height of the fuse portion-embedding resin member 25 and to fill the fuse portion-embedding resin member 25 to an appropriate height. This is the part for confirmation. As shown in FIGS. 7A and 7B, the fuse enclosing portion 24 has a first end surface 24a on the side opposite to the placement surface 13a. , at least one notch 26 recessed on the outer peripheral side and on the placement surface 13a side. 7(a) and 7(b) do not show the fuse portion-embedding resin member 25 in order to explain the notch portion 26. FIG. As shown in FIGS. 8(a) and 8(b), when the fuse portion-embedding resin member 25 is filled, the notch portion 26 is filled with the fuse portion-embedding resin member 25. By confirming this, it is possible to easily secure the accuracy of the predetermined filling height of the fuse portion-embedding resin member 25 .

In the present embodiment, the cross section of the notch surface of the notch portion 26 is a stepped surface including a surface facing the arrangement surface 13a and a surface facing the inner peripheral side. The cross-sectional shape of the notch surface of the notch portion 26 is not limited to a stepped surface. When the cross-sectional shape of the cutout surface of the cutout portion 26 is a stepped surface, the fuse portion-embedding resin member 25 is placed on the inner peripheral side of the cutout portion 26 when the fuse portion-embedding resin member 25 is filled. When reaching the facing surface, the fuse-embedding resin member 25 spreads to the outer circumference at once on the surface facing the inner circumference. can be easily confirmed.

The height at which the notch 26 is provided is a resin for embedding the fuse part 26, in which the melted member of the fuse part 23 melted when the fuse part 23 is melted is sufficiently dispersed inside the fuse enclosing part 24 and does not scatter outside. By setting the filling height of the member 25, the fuse part-embedding resin member 25 can be filled with an optimum filling amount at low cost. In addition, the melted member is sufficiently dispersed inside the fuse enclosing portion 24, and the filling height of the fuse portion-embedding resin member 25 that does not scatter to the outside is ensured. damage can be suppressed. The height at which the notch 26 is provided is determined in advance by experiments or the like. Since the magnitude of the current that flows during a short circuit differs depending on the specifications of the power converter 1, the height of the notch 26 is determined for each product. In this embodiment, the height from the placement surface 13a to the fuse portion 23 is, for example, about 2.5 mm to 3.0 mm, and the filling height of the fuse portion-embedding resin member 25 from the placement surface 13a is , for example, about 5.5 mm to 6.5 mm. Also, the distance from the fuse portion 23 to the fuse enclosing portion 24 is, for example, 3 mm or more.

As can be seen from a comparison between FIGS. 8A and 8B and FIGS. 9A and 9B, the filling height of the fuse portion-embedding resin member 25 is visually confirmed only at the notch portion 26. can be determined by Since the notch 26 easily secures the filling height of the fuse-embedding resin member 25, there is no need to use expensive equipment such as height measurement. Height inspection costs can be suppressed. Further, even when the filling height is inspected by inspection equipment, it is sufficient to confirm that the fuse portion-embedding resin member 25 is filled up to the notch portion 26 by image inspection. Therefore, even if there are a plurality of fuse portions 23, the surroundings of all the fuse portions 23 can be collectively checked at the same time. .

<Modification 1>
A modification of the power conversion device 1 according to the present embodiment will be described. FIG. 10 is a schematic plan view of another power conversion device 1 according to Embodiment 1, showing the fuse portion-embedding resin member 25 and a portion of the cylindrical portion 16a of the case 16 removed. The power conversion device 1 includes a plurality of power semiconductor elements (not shown), and one power conversion module 10 is formed from the plurality of power semiconductor elements. The bus bar 11 has a plurality of connection terminals 11b, and the plurality of connection terminals 11b are connected to the positive-side wiring members 17a to which the plurality of power semiconductor elements are respectively connected. A fuse enclosing portion 24 surrounds each of the plurality of fuse portions 23 in the plurality of connection terminals 11b. In FIG. 10, the power converter 1 has two power semiconductor elements and the bus bar 11 has two connection terminals 11b, but the number of power semiconductor elements and connection terminals 11b is not limited to this. The number may be three or more. Since a plurality of power conversion modules are formed by one power conversion module 10 by configuring in this way, the power conversion module 10 can be miniaturized. Since the power conversion module 10 is miniaturized, the power converter 1 can be miniaturized.

<Modification 2>
Another modification of the power conversion device 1 according to the present embodiment will be described. FIG. 11 is a schematic plan view of another power conversion device 1 according to Embodiment 1, in which the fuse portion-embedding resin member 25 and the cylindrical portion 16a of the case 16 are partially removed. The power conversion device 1 includes a plurality of power semiconductor elements (not shown), and each power conversion module 10 is formed from each of the plurality of power semiconductor elements. The bus bar 11 has a plurality of connection terminals 11b, and the plurality of connection terminals 11b are connected to the positive-side wiring members 17a to which the plurality of power semiconductor elements are respectively connected. One fuse enclosing portion 24 surrounds the plurality of fuse portions 23 in the plurality of connection terminals 11b. By configuring in this way, the distance between the adjacent fuse portions 23 can be shortened, so that the power conversion device 1 can be miniaturized. In addition, since the fuse enclosing part 24 is integrated into one, the number of filling times and the filling time of the fuse part-embedding resin member 25 can be reduced, so that the productivity of the power converter 1 can be improved. can.

<Modification 3>
Still another modified example of the power conversion device 1 according to the present embodiment will be described. FIG. 12 is a cross-sectional view showing a portion around the fuse portion 23 of another power converter 1 according to Embodiment 1. As shown in FIG. The fuse portion-embedding resin member 25 in Modification 3 is composed of a plurality of resin members having different viscosities. In the example shown in FIG. 12, the fuse portion-embedding resin member 25 is formed of a fuse portion-embedding resin member 25a and a fuse portion lower side resin member 25b, which are resin members having different viscosities. The fuse lower resin member 25b is arranged closer to the placement surface 13a than the fuse portion 23 and in contact with the placement surface 13a. The fuse lower resin member 25b has a higher viscosity than the fuse embedding resin member 25a. The fuse-embedding resin member 25a and the fuse-lower side resin member 25b may be different resin materials with different viscosities, or may be the same resin material with different viscosities (for example, silicone gel).

If air remains around the fuse portion 23 when the fuse portion-embedding resin member 25 is filled, it may cause problems such as heat generation. Therefore, the fuse portion-embedding resin member 25a made of a low-viscosity material is inserted into the fuse portion-embedding resin member 25 so that the fuse portion-embedding resin member 25 wraps around the fuse portion 23 without leaving any air. may be selected as On the other hand, between the fuse enclosing portion 24 of the case 16 and the arrangement surface 13a of the heat sink 13, a gap portion 27 may occur due to variations in finishing accuracy of the respective parts. If the gap 27 is formed, the low-viscosity fuse-embedding resin member 25 a may flow out from the gap 27 . In order to prevent the low-viscosity fuse-embedding resin member 25a from flowing out from the gap 27, the fuse-lower resin member 25b, which has a high viscosity and does not easily spread, is first filled to fill the gap 27. It is possible to prevent the low-viscosity fuse-embedding resin member 25 a from flowing out of the gap 27 .

With this configuration, when the fuse portion-embedding resin member 25 is filled, air enters around the fuse portion 23, and no air remains around the fuse portion 23. Therefore, the fuse can be closed during normal operation. The heat generated in the portion 23 can be easily radiated to the outside through the fuse portion-embedding resin member 25 around the fuse portion 23 . Since the heat generated in the fuse portion 23 is radiated to the outside, it is possible to suppress damage to peripheral components caused by the heat generation of the fuse portion 23 . The number of resin members having different viscosities is not limited to two, and resin members having three different viscosities may be filled step by step from the placement surface 13a side. In addition, the inside of the housing 12 may be further filled with another resin member for embedding the fuse portion-embedding resin member 25 and the power conversion module 10 . As a result, the inside of the power conversion device 1 can be protected from the effects of water exposure and the like.

As described above, in the power conversion device 1 according to Embodiment 1, the connection terminal 11b extending from the body portion of the bus bar 11 has the fuse portion 23 having a smaller cross-sectional area than the front and rear portions, and the case 16 It has a fuse enclosing portion 24 surrounding the fuse portion 23 when viewed in a direction perpendicular to the placement surface 13a, the fuse portion 23 is exposed from the case 16, and the fuse enclosing portion 24 is on the side opposite to the placement surface 13a. and at least one cutout portion 26 recessed toward the outer peripheral side and the arrangement surface 13a at the inner peripheral end of the first end face 24a. Since the fuse portion-embedding resin member 25 in which the fuse portion 23 is embedded is filled from the arrangement surface 13a to a position where the notch portion 26 is partially or wholly buried, the notch portion 26 is provided at a height When the fuse portion 23 is melted, the melted member of the fuse portion 23 is sufficiently dispersed inside the fuse enclosing portion 24 and does not scatter to the outside. By setting as follows, the fuse portion-embedding resin member 25 can be filled with an optimum filling amount at low cost. In addition, the melted member is sufficiently dispersed inside the fuse enclosing portion 24, and the filling height of the fuse portion-embedding resin member 25 that does not scatter to the outside is ensured. damage can be suppressed.

When the cross section of the notch surface of the notch portion 26 is a stepped surface composed of a surface facing the arrangement surface 13a and a surface facing the inner peripheral side, when filling the fuse portion-embedding resin member 25, the fuse is When the fuse portion-embedding resin member 25 reaches the inner peripheral surface of the notch portion 26, the fuse portion-embedding resin member 25 spreads at once toward the outer peripheral side of the inner peripheral surface. It is possible to easily confirm the arrival of the surface of the notch portion 26 of the embedding resin member 25 toward the inner peripheral side.

When the fuse portion-embedding resin member 25 is composed of a plurality of resin members having different viscosities, air does not remain around the fuse portion 23, so heat generated in the fuse portion 23 during normal operation is dissipated around the fuse portion 23. The heat can be easily dissipated to the outside through the fuse part embedding resin member 25. Since the heat generated in the fuse portion 23 is radiated to the outside, it is possible to suppress damage to peripheral components caused by the heat generation of the fuse portion 23 .

A plurality of connection terminals 11b of the bus bar 11 are connected to a positive electrode side wiring member 17a to which a plurality of power semiconductor elements are respectively connected, and the plurality of fuse portions 23 of the plurality of connection terminals 11b are combined into one fuse. When the enclosing part 24 surrounds, the distance between adjacent fuse parts 23 can be shortened, so that the power converter 1 can be miniaturized. In addition, since the fuse enclosing part 24 is integrated into one, the number of filling times and the filling time of the fuse part-embedding resin member 25 can be reduced, so that the productivity of the power converter 1 can be improved. can.

Embodiment 2.
A power converter 1 according to Embodiment 2 will be described. FIG. 13 is a diagram showing a main part of the power conversion device 1 according to Embodiment 2. As shown in FIG. 13(a) is a perspective view showing a portion around the fuse portion 23, with the fuse portion-embedding resin member 25 removed, and FIG. 13(b) shows a portion around the fuse portion 23. FIG. 2 is a cross-sectional view showing the fuse portion-embedding resin member 25 removed. FIG. In the power conversion device 1 according to the second embodiment, the cross-sectional shape of the notch surface of the notch portion 26 is different from that of the first embodiment.

A cross-section of the notch surface of the notch portion 26 is a curved surface 26a recessed toward the outer peripheral side and the arrangement surface 13a side. In this embodiment, the shape of the curved surface 26a is the shape of a 1/4 side surface along the extending direction of the cylinder. The shape of the curved surface 26a is not limited to this. By manufacturing the case 16 by molding using a molding die, the manufacturing cost of the case 16 can be suppressed. With the shape of the notch portion 26 in Embodiment 1, there is a high release resistance when releasing from the mold after molding, so there is a possibility that the yield after releasing the mold will deteriorate. By forming the cross section of the cutout surface of the cutout portion 26 into a curved surface 26a that is recessed toward the outer peripheral side and the arrangement surface 13a side, mold releasing resistance can be reduced and the yield can be improved. Since the yield is improved, the cost of the power converter 1 can be suppressed. Moreover, since the volume of the notch portion 26 is reduced, the filling amount of the fuse portion-embedding resin member 25 is reduced, so that the cost of the power conversion device 1 can be suppressed.

Embodiment 3.
A power converter 1 according to Embodiment 3 will be described. FIG. 14 is a diagram showing a main part of the power conversion device 1 according to Embodiment 3. As shown in FIG. 14(a) is a perspective view showing a portion around the fuse portion 23, with the fuse portion-embedding resin member 25 removed, and FIG. 14(b) shows a portion around the fuse portion 23. FIG. 2 is a cross-sectional view showing the fuse portion-embedding resin member 25 removed. FIG. In the power conversion device 1 according to the third embodiment, the cross-sectional shape of the notch surface of the notch portion 26 is different from that of the first embodiment.

A cross-section of the cutout surface of the cutout portion 26 is an inclined surface 26b directed toward the arrangement surface 13a as it goes toward the inner peripheral side. The smaller angle of the inclined surface 26b with respect to the placement surface 13a is, for example, 45 degrees, but the angle of the inclined surface 26b is not limited to this. By manufacturing the case 16 by molding using a molding die, the manufacturing cost of the case 16 can be suppressed. With the shape of the notch portion 26 in Embodiment 1, there is a high release resistance when releasing from the mold after molding, so there is a possibility that the yield after releasing the mold will deteriorate. By making the cross-section of the cutout surface of the cutout portion 26 a sloped surface 26b directed toward the arrangement surface 13a toward the inner peripheral side, mold release resistance can be reduced and the yield can be improved. Since the yield is improved, the cost of the power converter 1 can be suppressed. Further, since the volume of the notch portion 26 is smaller than that of the curved surface 26a shown in the second embodiment, the filling amount of the fuse portion-embedding resin member 25 is further reduced. Costs can be further reduced.

Embodiment 4.
A power converter 1 according to Embodiment 4 will be described. FIG. 15 is a diagram showing a main part of the power conversion device 1 according to Embodiment 4. As shown in FIG. 15(a) is a perspective view showing a portion around the fuse portion 23, with the fuse portion-embedding resin member 25 removed, and FIG. 15(b) shows a portion around the fuse portion 23. FIG. 2 is a plan view showing the fuse portion-embedding resin member 25 removed. FIG. The power conversion device 1 according to the fourth embodiment has a different number of notches 26 from that of the first embodiment.

The fuse enclosing portion 24 has a plurality of cutouts 26 . In the present embodiment, the shape of the inner periphery of one fuse enclosing portion 24 is rectangular when viewed in the direction perpendicular to the arrangement surface 13a, and one notch portion 26 is provided on each of three of the four sides. is formed. The number of notches 26 is not limited to three, and notches 26 may be formed on all sides. If the electric power conversion device 1 is slightly tilted before the fuse-embedding resin member 25 filled in the fuse enclosing portion 24 hardens, the filling height of the fuse-embedding resin member 25 varies. It will be. If there is only one notch 26 , the filling height of the fuse-embedding resin member 25 on the side of the fuse enclosing part 24 where there is no notch 26 cannot be confirmed by the notch 26 .

By providing a plurality of cutouts 26, even if the electric power conversion device 1 is slightly tilted, the filling height of the fuse portion-embedding resin member 25 can be confirmed at each of the plurality of cutouts 26. can be done. Since the filling height of the fuse part-embedding resin member 25 can be confirmed at each of the plurality of cutouts 26, the filling height of the fuse part-embedding resin member 25 can be reliably secured. Variations in filling height of the members 25 can be managed more stably. Note that the cross-sectional shape of the cutout surface of the cutout portion 26 formed at a plurality of locations may be any of the shapes shown in the first to third embodiments.

Embodiment 5.
A power converter 1 according to Embodiment 5 will be described. FIG. 16 is a diagram showing a main part of the power conversion device 1 according to Embodiment 5. As shown in FIG. 16(a) is a perspective view showing a portion around the fuse portion 23, with the fuse portion-embedding resin member 25 removed, and FIG. 16(b) shows a portion around the fuse portion 23. FIG. 2 is a plan view showing the fuse portion-embedding resin member 25 removed. FIG. The power conversion device 1 according to Embodiment 5 has a configuration in which the notch portion 26 is formed at a specific location.

The notch portion 26 is formed in a portion of the fuse enclosing portion 24 facing the direction perpendicular to the extending direction of the fuse portion 23 when viewed in the direction perpendicular to the arrangement surface 13a. The notch portion 26 is not formed in the portion of the fuse enclosing portion 24 on the side where the connection terminal 11b having the fuse portion 23 is exposed. In the present embodiment, the shape of the inner peripheral side of one fuse enclosing portion 24 is rectangular when viewed in the direction perpendicular to the placement surface 13a, and the direction perpendicular to the extending direction of the fuse portion 23 among the four sides is rectangular. One notch portion 26 is formed on each of two sides facing the . The cross-sectional shape of the cutout surface of the cutout portion 26 may be any of the shapes shown in the first to third embodiments.

Since the fuse portion 23 has a small cross-sectional area of the current-carrying portion, it generates a large amount of heat even during normal operation, and tends to increase the temperature of surrounding members via the connection terminal 11b. When the notch portion 26 is provided in the portion of the fuse enclosing portion 24 on the side where the connection terminal 11b is exposed, the volume of the portion of the fuse enclosing portion 24, which is a peripheral member for releasing the heat of the fuse portion 23 transmitted from the connection terminal 11b, is reduced. Therefore, the temperature of the peripheral members is further increased. By forming the notch portion 26 in the portion of the fuse enclosing portion 24 facing the direction perpendicular to the extending direction of the fuse portion 23 when viewed in the direction perpendicular to the arrangement surface 13a, the fuse portion transmitted from the connection terminal 11b is formed. Since the volume of the portion of the fuse enclosing portion 24, which is a peripheral member that releases the heat of 23, does not decrease, it is possible to suppress the temperature rise of the peripheral members via the connection terminal 11b.

Also, while this application has described various exemplary embodiments and examples, various features, aspects, and functions described in one or more of the embodiments may vary from particular embodiment to specific embodiment. The embodiments are applicable singly or in various combinations without being limited to the application.
Accordingly, numerous variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, modification, addition or omission of at least one component, extraction of at least one component, and combination with components of other embodiments shall be included.

Reference Signs List 1 power conversion device 10 power conversion module 11 busbar 11a main body 11b connection terminal 12 housing 13 heat sink 13a placement surface 13b protrusion 13c outer surface 14 power semiconductor element 15 fin 16 case , 16a cylindrical portion, 17 wiring member, 17a wiring member on the positive electrode side, 17a1 connection end portion, 17b wiring member on the output side, 17b1 connection end portion, 17c wiring member on the negative electrode side, 17c1 connection end portion, 18 wiring for semiconductor element Member 19 Control terminal 20 Conductive bonding material 21 Mold resin 22 Heat dissipation member 23 Fuse part 24 Fuse enclosing part 24a First end face 25 Fuse part embedding resin member 25a Fuse part embedding Resin member 25b Fuse lower resin member 26 Notch 26a Curved surface 26b Inclined surface 27 Gap

Claims (9)

a power semiconductor element;
a heat sink having an arrangement surface to which the power semiconductor element is thermally connected;
a bus bar that supplies power to the power semiconductor element;
a case arranged on the arrangement surface and integrally formed with the bus bar,
The bus bar has a main body and a connection terminal extending from the main body and connected to a wiring member of the power semiconductor element,
the connection terminal has a fuse portion extending along the arrangement surface and having a smaller cross-sectional area than the front and rear portions;
the case has a fuse enclosing portion that surrounds the fuse portion and protrudes in a direction toward the power semiconductor element from a case body integrally formed with the bus bar when viewed in a direction perpendicular to the arrangement surface; the fuse portion is exposed from the case, the fuse enclosing portion is formed in a cylindrical shape and surrounds the fuse portion;
The fuse enclosing portion has a first end face opposite to the placement face, and at least one notch recessed toward the outer periphery and the placement face on the inner peripheral end of the first end face. has a part
A power conversion device, wherein the inside of the fuse enclosing portion is filled with a fuse portion-embedding resin member that embeds the fuse portion from the arrangement surface to a position where the notch portion is partially or wholly buried. a power semiconductor element;
a heat sink having an arrangement surface to which the power semiconductor element is thermally connected;
a bus bar that supplies power to the power semiconductor element;
a case arranged on the arrangement surface and integrally formed with the bus bar,
The bus bar has a main body and a connection terminal extending from the main body and connected to a wiring member of the power semiconductor element,
the connection terminal has a fuse portion extending along the arrangement surface and having a smaller cross-sectional area than the front and rear portions;
the case has a fuse enclosing portion surrounding the fuse portion when viewed in a direction perpendicular to the arrangement surface, the fuse portion being exposed from the case;
The fuse enclosing portion has a first end face opposite to the placement face, and at least one notch recessed toward the outer periphery and the placement face on the inner peripheral end of the first end face. has a part
The inside of the fuse enclosing portion is filled with a fuse portion-embedding resin member that embeds the fuse portion from the arrangement surface to a position where the notch portion is partially or wholly buried,
The fuse portion-embedding resin member is formed of two resin members having different viscosities, namely, a body portion of the fuse portion-embedding resin member in which the fuse portion is embedded and a fuse portion lower side resin member,
The fuse lower side resin member has a higher viscosity than the main body portion of the fuse embedding resin member,
A power conversion device in which the resin member for the lower side of the fuse section is disposed closer to the arrangement surface than the fuse section, away from the fuse section, and in contact with the arrangement surface. The power converter according to claim 1 or 2, wherein a cross section of the notch surface of the notch portion is a curved surface recessed toward the outer circumference side and the arrangement surface side. The power conversion device according to claim 1 or 2, wherein a cross section of the notch surface of the notch portion is an inclined surface toward the arrangement surface side as it goes toward the inner peripheral side. 3. The power converter according to claim 1, wherein a cross section of the notch surface of the notch portion is a stepped surface including a surface facing the arrangement surface and a surface facing the inner peripheral side. The power converter according to any one of claims 1 to 5, wherein the fuse enclosing portion has a plurality of the notch portions. 6. The cutout portion is formed in a portion of the fuse enclosing portion facing the direction perpendicular to the extending direction of the fuse portion when viewed in the direction perpendicular to the arrangement surface. 1. The power conversion device according to item 1. comprising a plurality of the power semiconductor elements,
The bus bar has a plurality of connection terminals,
the plurality of connection terminals are connected to the respective wiring members of the plurality of power semiconductor elements,
6. The power converter according to any one of claims 1 to 5, wherein the fuse enclosing portion surrounds the plurality of fuse portions in the plurality of connection terminals. A direction in which the busbar extends parallel to the arrangement surface is defined as a first direction, a direction parallel to the arrangement surface and perpendicular to the first direction is defined as a second direction,
A plurality of sets of the power semiconductor elements are provided, and the plurality of power semiconductor elements are arranged side by side in the second direction ,
The fuse portion and the fuse enclosing portion are provided on one side of each of the plurality of power semiconductor elements in the first direction ,
The bus bar and the case main body are provided as a set for the plurality of the fuse sections and the plurality of the fuse enclosing sections, and are arranged on one side of the plurality of the fuse sections and the plurality of the fuse enclosing sections in the first direction. extending in the second direction ;
2. The power converter of claim 1, wherein each of said fuse enclosures are spaced apart in said second direction .

Images