Patent ID: 12206336

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, a detailed description is hereinafter provided of power converters according to embodiments of the present disclosure.

First Embodiment

FIG.1is a diagram illustrating a configuration of a converter according to a first embodiment. In a description provided below, two axes orthogonal to each other in a plane parallel to a top face of the converter101, which is a power converter, are an X-axis and a Y-axis. An axis orthogonal to the X- and Y-axes is a Z-axis. A body case1of the converter101is, for example, a rectangular parallelepiped, with its top and bottom faces parallel to an X-Y plane. In the following description, the body case1is described to have two side faces parallel to an X-Z plane and a front and a back face parallel to a Y-Z plane. The terms “top face”, “bottom face”, “side face”, “front face”, and “back face” of the body case1are used as convenient names for respectively describing the faces of the body case1and do not determine actual orientation of the converter101.

The converter101internally includes one or more diode modules4. The converter101includes, for example, a rectification function of converting three-phase AC into direct current (DC). The converter101may be disposed inside an inverter.

The converter101includes the body case1and a cooling fin3as an exterior. The body case1includes, in a part, body case slits2intended for exchange of internal air of the converter101and external air. The body case slits2are openings in the body case1. The slit-shaped openings of the body case1are not limiting. The openings may be of any shapes. The body case1of the converter101houses the diode module(s)4.

The diode module4disposed in the converter101includes a diode bridge housed in a case (later described as a module case10). The module case10is in physical contact with the cooling fin3at a face (bottom face).

The module case10is, for example, a rectangular parallelepiped, with its top and bottom faces parallel to the X-Y plane. The module case10has two side faces parallel to the X-Z plane and a front and a back face parallel to the Y-Z plane. The terms “top face”, “bottom face”, “side face”, “front face”, and “back face” of the module case10are used as convenient names for respectively describing the faces of the module case10and do not determine actual orientation of the module case10.

The diode module4is disposed in the converter101, with the front face of the diode module4facing a placement face (first face)15for the body case slits2. In other words, the placement face15for the body case slits2is parallel to the Y-Z plane. When viewed from the front face of the diode module4, a right-hand one of the side faces of the diode module4is a right side face, while a left-hand one is a left side face.

Among exterior wall faces serving as a covering of the module case10, a counter face facing the placement face15for the body case slits2is a face having an angle of less than 90 degrees relative to the placement face15for the body case slits2. Any noncounter face not facing the placement face15for the body case slits2is a face having an angle of 90 degrees or more relative to the placement face15for the body case slits2.

For the diode module4illustrated inFIG.1, its front face refers to the counter face that faces the placement face15for the body case slits2, and its other faces refer to the noncounter faces.

The orientation of the diode module4with respect to the body case slits2is crucial in the converter101.FIG.1andFIGS.2to5to be mentioned later illustrate a reference point5on the top face of the diode module4for convenience of explanation. The orientation of the diode module4with respect to the body case slits2is described with the use of the reference point5. The reference point5is a point near a vertex connecting with the top face, the right side face, and the back face of the diode module4.

The diode module4includes the at least one diode bridge that has a rectification function. The diode module4may be a commonly called insulated gate bipolar transistor (IGBT) module, a module where switching elements and a diode bridge are connected in parallel. Alternatively, the diode module4may be a commonly called intelligent power module, a module where switching elements and a diode bridge are connected in parallel, with a circuit that drives the switching elements connected.

FIG.2is a diagram illustrating a configuration of a diode module included in the converter according to the first embodiment. The diode module4A is an example of the diode module4.

The diode module4A includes a breakage prevention structure6A at an exterior wall portion. The breakage prevention structure6A is disposed, for example, on a face with a largest area among faces (exterior wall faces) serving as a covering of the diode module4A. The module case10of the diode module4A inFIG.2is described to have the top face11and the bottom face as the faces with the largest areas among the exterior wall faces, which serve as the covering of the diode module4A. The face with the largest area refers to any face that has a largest area when viewed in a direction parallel to a normal vector. In other words, in cases where there are plural faces with the same area when viewed in directions parallel to a normal vector, those plural faces are faces with largest areas.

The breakage prevention structure6A illustrated inFIG.2is disposed on the top face11of the module case10of the diode module4A. The diode module4A ofFIG.2is assumed to be disposed like the diode module4ofFIG.1inside the converter101. In other words, the diode module4A is disposed inside the converter101, with the front face12of the module case10facing the placement face15for the body case slits2. The reference point5is the point near the vertex20connecting with the top face11, the right side face13, and the back face among the exterior wall faces. In other words, the reference point5is positioned on the top face11of the module case10, away from the body case slits2. Among the exterior wall faces of the module case10, the front face12refers to the counter face that faces the placement face15for the body case slits2, and the other faces refer to the noncounter faces. The top face11among the exterior wall faces of the module case10is a noncounter placement face. In cases where there are plural faces with largest areas among the noncounter faces of the module case10, the breakage prevention structure6A may be disposed on at least one of those faces.

The breakage prevention structure6A has a shape that covers a portion of the top face11of the diode module4A but not a remaining portion (nonplacement area7A) of the top face11. The nonplacement area7A is an area including the reference point5.FIG.2illustrates the nonplacement area7A as a triangular area including the reference point5. The nonplacement area7A is the area of the top face11of the module case10that is farther from the placement face15than a middle of the top face11is. In other words, while the nonplacement area7A ofFIG.2is described as the triangular area that includes the reference point5, the nonplacement area7A may have, for example, a polygonal shape, a circular shape, or another shape, as long as the nonplacement area7A is farther from the placement face15than the middle of the top face11is and is the area of the top face11where the breakage prevention structure6A is not disposed. Since the reference point5is illustrated for the convenience of explanation, it goes without saying that the nonplacement area7A does not need to include the reference point5. The breakage prevention structure6A is an example of a second breakage prevention structure.

The breakage prevention structure6A is noncombustible. The breakage prevention structure6A includes, for example, a hard material or an adhesive. The breakage prevention structure6A is disposed in close contact with the top face11of the module case10and prevents or lessens breakage of a closely contacting portion of the module case10when the diode module4A is about to be destroyed (to explode) from within.

Examples of the hard material as a material for the breakage prevention structure6A include poly butylene terephthalate (PBT) and epoxy glass, among others. Examples of the adhesive include polycarbonate, among others.

The breakage prevention structure6A has a role of receiving impact of the breakage of the diode module4A. Therefore, the breakage prevention structure6A may be affixed to the diode module4A to be fixed or may be fixed to a fixed part that remains intact even when the diode module4A breaks (such as the cooling fin3inFIG.1or another part). The breakage prevention structure6A may be disposed in any way that enables the breakage prevention structure6A to receive the impact of the breakage of the diode module4A. For example, the breakage prevention structure6A may be fixed by being disposed and held between a component (not illustrated) of the converter101and the diode module4A inside the body case1of the converter101.

As illustrated inFIG.2, the diode module4A has the breakage prevention structure6A disposed. Therefore, during the destruction of the diode module4A, the portion where the breakage prevention structure6A is disposed is not destroyed. In other words, during the destruction of the diode module4A, a part where the breakage prevention structure6A is not disposed is destroyed. For example, the nonplacement area7A and others are destroyed during the destruction of the diode module4A. In the first embodiment, among the exterior wall faces, which serve as the covering of the diode module4A, the top face11is the face with the largest area and is most susceptible to force from inside the module case10, thus being most likely to be destroyed. By having the portion where the breakage prevention structure6A is disposed and the nonplacement area7A where the breakage prevention structure6A is not disposed, the top face11of the module case10, the face with the largest area that is most susceptible to the force from inside the module case10, is enabled to have a strength difference and direct destruction to the nonplacement area7A.

As described above, when the noncounter face among the exterior wall faces of the module case10is where the breakage prevention structure6A is disposed, for the diode module4A, the noncounter face where the breakage prevention structure6A is disposed is the top face11(noncounter placement face), which is the noncounter face with the largest area among the exterior wall faces of the module case10. Furthermore, for the diode module4A, the top face11where the breakage prevention structure6A is disposed has the portion of an area farther from the placement face15than the middle of the top face11is as the nonplacement area7A.

Since the module case10of the diode module4A according to the first embodiment has the portion (nonplacement area7A) where the breakage prevention structure6A is not disposed and the portion where the breakage prevention structure6A is disposed, the destruction can be directed to the portion to be destroyed during the destruction of the diode module4A. In other words, the diode module4A is capable of directing the destruction to the nonplacement area7A of the module case10, where the breakage prevention structure6A is not disposed.

For the module case10of the diode module4A of the first embodiment, the nonplacement area7A where the breakage prevention structure6A is not disposed is the portion farther from the body case slits2of the converter101ofFIG.1. Therefore, during the destruction of the diode module4A in the converter101, debris can be prevented from going out of the converter101through the body case slits2. In other words, the nonplacement area7A, being the area farther from the placement face15for the body case slits2, can prevent a sealing material filled into the diode module4A from bursting out through the body case slits2despite the destruction of the diode module4A.

The shape of the nonplacement area7A where the breakage prevention structure6A is not disposed can be variously set, depending on shape of the converter101, the location of the body case slits2in the body case1of the converter101, shape of each body case slit2, location of the diode module4A inside the converter101, and the shape of the diode module4A, among others.

FIG.3is a diagram illustrating a diode module with another configuration example that is included in the converter according to the first embodiment. The diode module4B is an example of the diode module4. As with the diode module4A, the diode module4B is assumed to be disposed like the diode module4ofFIG.1inside the converter101.

As in the diode module4A, the module case10of the diode module4B has the top face11and the bottom face as faces with largest areas among exterior wall faces serving as a covering of the diode module4B.

As illustrated inFIG.3, the diode module4B, which features the different configuration example for the diode module4, includes a breakage prevention structure6B instead of the breakage prevention structure6A, as compared with the diode module4A. As with the breakage prevention structure6A, the breakage prevention structure6B includes a noncombustible hard material or a noncombustible adhesive.

The breakage prevention structure6B is a rectangular plate-shaped member. On the top face11of the module case10of the diode module4B, the breakage prevention structure6B is disposed closer to the placement face15for the body case slits2than the middle of the top face11is.

Compared with the diode module4A, the diode module4B includes a nonplacement area7B instead of the nonplacement area7A. The nonplacement area7B is a rectangular area. As with the nonplacement area7A, the nonplacement area7B is an area including the reference point5. The nonplacement area7B is the area of the top face11of the module case10that is farther from the placement face15than the middle of the top face11is. As with the above-described nonplacement area7A, the nonplacement area7B only has to be the area of the top face11where the breakage prevention structure6B is not disposed and be farther from the placement face15than the middle of the top face11is. The nonplacement area7B may have, for example, a polygonal shape, a circular shape, or another shape. Since the reference point5is illustrated for the convenience of explanation, it goes without saying that the nonplacement area7B does not need to include the reference point5. The breakage prevention structure6B is an example of the second breakage prevention structure.

The shape of each of the diode modules4A and4B is not limited to the rectangular parallelepiped and may be a prism other than the rectangular parallelepiped. In that case as well, each of the prism-shaped diode modules4A and4B is disposed, with at least one of its faces that do not have largest areas facing the placement face15for the body case slits2, a breakage prevention structure is disposed on the top face11of each of the diode modules4A and4B, and each of the diode modules4A and4B includes a nonplacement area. As with the nonplacement areas7A and7B, the nonplacement area in that case, too, is on a side opposite to the placement face15for the body case slits

A description is provided here of a diode module as a comparative example (hereinafter referred to as “comparative diode module”). A module case of the comparative diode module has an entire surface covered with a breakage prevention structure. This comparative diode module can experience destruction that exceeds a design assumption. In the case of this comparative diode module, a face with a largest area, for example, is highly likely to receive a significant force and be destroyed. When, for example, the comparative diode module has the face with the largest area as a top face and is destroyed near body case slits, broken pieces of a component of the comparative diode module can scatter out of the comparative diode module and then out of a converter through the body case slits. In this case, reliability of equipment disposed externally to the converter is deteriorated. In addition, the special structure provided for the comparative diode module to prevent destruction causes design complexity and complexity of a manufacturing process, resulting in lower reliability of the comparative diode module and increased manufacturing costs.

For the diode modules4A and4B according to the first embodiment, on the other hand, the destruction of each of the diode modules4A and4B is directed to the portion (nonplacement area7A or7B) that allows for a smaller impact of destruction, that is to say, the portion farther from the body case slits2. Therefore, broken pieces generated by the destruction can be prevented from scattering out of the converter101during the destruction of each of the diode modules4A and4B. The diode modules4A and4B are based on the assumption that the diode modules4A and4B each experience destruction that exceeds a design assumption, and as described above, each direct, when the destruction occurs, the destruction to the portion where broken pieces that result from the destruction do not scatter out of the converter101. In addition, the diode modules4A and4B themselves do not require special structures, thus each preventing an increase in manufacturing costs because of no design complexity and no complexity of a manufacturing process.

As described above, the module case10of each of the diode modules4A and4B according to the first embodiment includes the portion where the breakage prevention structure6A or6B is disposed and the nonplacement area7A or7B where the breakage prevention structure6A or6B is not disposed, with consideration given to the placement of the diode module4A or4B inside the converter101. Accordingly, during the destruction of each of the diode modules4A and4B that exceeds the design assumption, the converter101can direct the destruction to the nonplacement area7A or7B.

Therefore, even when destruction occurs to such an extent that broken pieces of a component of the diode module4A or4B are scattered out of the diode module4A or4B, the converter101can reliably prevent the broken pieces, which are debris, from scattering out of the converter101. Consequently, despite the destruction of the diode module4A or4B, the converter101allows for maintained reliability of equipment disposed externally to the converter101.

Second Embodiment

With reference toFIG.4, a description is provided next of a second embodiment. In the second embodiment, a breakage prevention structure is disposed on the front face12of the module case10of a diode module. The front face12of the module case10is not illustrated inFIG.4and the subsequent drawings.

FIG.4is a diagram illustrating a configuration of the diode module included in a converter according to the second embodiment. The diode module4C is an example of the diode module4. As with the diode module4A, the diode module4C is assumed to be disposed like the diode module4ofFIG.1inside the converter101.

Unlike the diode modules4A and4B, the diode module4C features the front face12of the module case10(that corresponds to the front face12ofFIG.2) as a face with a largest area among exterior wall faces serving as a covering of the diode module4C. The front face12of the diode module4C is a counter face facing the placement face (first face)15for the body case slits2of the converter101. The diode module4C is such that the disposed breakage prevention structure6C entirely covers the front face12(counter face) of the module case10. As with the breakage prevention structure6A, the breakage prevention structure6C includes a noncombustible hard material or a noncombustible adhesive.

The breakage prevention structure6C is disposed, entirely covering the front face12of the module case10of the diode module4C. In other words, the front face12of the module case10of the diode module4C has no nonplacement area. The breakage prevention structure6C is an example of a first breakage prevention structure.

As described above, the diode module4C according to the second embodiment is disposed, with the front face12of the module case10where the breakage prevention structure6C is disposed facing the placement face15for the body case slits2. In other words, for the diode module4C, since the counter face (front face), which faces the placement face15among the exterior wall faces of the module case10, has the largest area compared with noncounter faces that are exterior wall faces other than the counter face, the breakage prevention structure6C is disposed on the counter face to prevent a breakage of the module case10. No breakage prevention structures6C are disposed on the noncounter faces among the exterior wall faces of the module case10. For the diode module4C, no breakage prevention structures6C may be disposed on some or all of the noncounter faces. In other words, there can be a configuration such that no breakage prevention structures6C are disposed on at least some of the noncounter faces.

As described above, the diode module4C has the disposed breakage prevention structure6C that covers the entire front face12of the module case10. Therefore, during destruction of the diode module4C, the portion where the breakage prevention structure6C is disposed is not destroyed. On the other hand, the faces with no breakage prevention structures6C, that is to say, the faces other than the front face among the exterior wall faces, which serve as the covering of the diode module4C, can be destroyed. This means that by having the breakage prevention structure6C disposed on the entire counter face, the diode module4C is enabled to have a strength difference between the counter face and the noncounter faces where no breakage prevention structures6C are disposed and direct the destruction to the noncounter faces, which do not face the body case slits2.

The diode module4C may be disposed so that two of the faces of the module case10of the diode module4C, namely the front face and one of the side faces (e.g., the right side face13), face the placement face15for the body case slits2. In that case, the entire front face and the right side face13of the module case10of the diode module4C are counter faces, and the breakage prevention structures6C are disposed on the entire front face and the entire right side face13. For example, the breakage prevention structures6C are disposed on the front face12and the right side face13of the module case10when the placement face15for the body case slits2forms an angle of less than 90 degrees with the front face12of the module case10of the diode module4C and an angle of less than 90 degrees with the right side face13of the module case10of the diode module4C.

The diode module4C is not limited to the shape of a rectangular parallelepiped, and its shape may be a prism other than the rectangular parallelepiped. In that case as well, the prism-shaped diode module4C is disposed, with at least one of its faces facing the placement face15for the body case slits2, and a breakage prevention structure is disposed on the counter face that faces the placement face15among the faces of the diode module4C.

As described above, the module case10of the diode module4C according to the second embodiment includes the face (front face) where the breakage prevention structure6C is disposed and the faces where no breakage prevention structures6C are disposed, with consideration given to the placement of the diode module4C inside the converter101. Accordingly, during the destruction of the diode module4C, the converter101can direct the destruction to the faces other than the counter face of the module case10.

Therefore, even when destruction occurs to such an extent that broken pieces of a component of the diode module4C are scattered out of the diode module4C, the converter101can reliably prevent the broken pieces, which are debris, from scattering out of the converter101. Consequently, despite the destruction of the diode module4C, the converter101allows for maintained reliability of equipment disposed externally to the converter101.

Third Embodiment

With reference toFIG.5, a description is provided next of a third embodiment. In the third embodiment, the front face12of the module case10of a diode module is where a breakage prevention structure larger than the front face12is disposed.

FIG.5is a diagram illustrating a configuration of the diode module included in a converter according to the third embodiment. The diode module4D is an example of the diode module4. As with the diode module4A, the diode module4D is assumed to be disposed like the diode module4ofFIG.1inside the converter101.

As with the diode module4C, the diode module4D features the front face12of the module case10(that corresponds to the front face12ofFIG.2) as a face with a largest area among exterior wall faces serving as a covering of the diode module4D. The front face of the diode module4D is a counter face facing the placement face (first face)15for the body case slits2of the converter101. The diode module4D is such that the disposed breakage prevention structure6D entirely covers the front face12(counter face) of the module case10. As with the breakage prevention structure6A, the breakage prevention structure6D includes a noncombustible hard material or a noncombustible adhesive.

The breakage prevention structure6D has a larger area than the front face12of the module case10of the diode module4D. This means that a face (back face) of the breakage prevention structure6D that faces the front face12of the module case10has the larger area than the front face12of the module case10. In other words, the face of the breakage prevention structure6D includes an area in contact with the counter face (front face12of the module case10) of the diode module4D and has the larger area than the front face12of the module case10. The breakage prevention structure6D is disposed, entirely covering the front face12of the module case10of the diode module4D. In other words, the front face12of the module case10of the diode module4D has no nonplacement area. The breakage prevention structure6D is an example of the first breakage prevention structure.

A portion of the breakage prevention structure6D that is not in contact with the front face12of the module case10extends longitudinally of the body case slits2. In other words, the breakage prevention structure6D is positioned, facing the body case slits2. For example, the breakage prevention structure6D becomes protrusive from the top face11of the module case10of the diode module4D that is a noncounter face extending in a direction intersecting the front face12, which is the counter face. When the interior of the converter101is seen from outside the converter101through the body case slits2, the diode module4D is hidden from view by the disposed breakage prevention structure6D. No breakage prevention structures6D are disposed on those noncounter faces among the exterior wall faces of the module case10. For the diode module4D, no breakage prevention structures6D may be disposed on some or all of the noncounter faces. In other words, there can be a configuration such that no breakage prevention structures6D are disposed on at least some of the noncounter faces.

As described above, the module case10of the diode module4D according to the third embodiment includes the face (front face) where the breakage prevention structure6D is disposed and the faces where no breakage prevention structures6D are disposed, with consideration given to the placement of the diode module4D inside the converter101. Accordingly, during destruction of the diode module4D, the converter101can direct the destruction to the faces other than the front face.

Furthermore, the breakage prevention structure6D has the portion protruding from the top face11of the module case10, so that during the destruction of the diode module4D, broken pieces scattering from the top face11of the module case10can be prevented from scattering out of the converter101.

Therefore, even when destruction occurs to such an extent that broken pieces of a component of the diode module4D are scattered out of the diode module4D, the converter101can reliably prevent the broken pieces, which are debris, from scattering out of the converter101. Consequently, despite the destruction of the diode module4D, the converter101allows for maintained reliability of equipment disposed externally to the converter101.

In the first through third embodiments, the breakage prevention structures6C and6D are the first breakage prevention structures, and the breakage prevention structures6A and6B are the second breakage prevention structures.

A description is provided here of modifications of the second and third embodiments.FIG.6is a diagram illustrating a diode module with another configuration example that is included in the converter according to the second embodiment.FIG.7is a diagram illustrating a diode module with another configuration example that is included in the converter according to the third embodiment. The diode module4C′ illustrated inFIG.6is a modification of the diode module4C illustrated inFIG.4, and the diode module4D′ illustrated inFIG.7is a modification of the diode module4D illustrated inFIG.5.

In the above-described second and third embodiments, the front faces of the diode modules4C and4D, namely the counter faces, each have been described to have the largest area among the exterior wall faces and be where the breakage prevention structure6C or6D is disposed. However, each of the breakage prevention structures6C and6D only has to be disposed to cover the entire counter face that faces the face (first face) with the body case slits2of the body case1of the converter101. For example, as illustrated inFIGS.6and7, the diode modules4C′ and4D′ may be configured, each having, among exterior wall faces of the module case10, a counter face facing the placement face (first face)15for the body case slits2of the converter101as the front face and a noncounter face with a largest area that extends in a direction (X direction) intersecting the counter face as the top face11, with a breakage prevention structure6C′ or6D′ being disposed and entirely covering the front face that has a smaller area than the top face11and with no breakage prevention structures6C′ or6D′ disposed on noncounter faces including the top face11. In these cases, destruction can be easily directed to the top face11with the largest area among the exterior wall faces of the module case10, allowing for an effect similar to those of the above-described second and third embodiments.

In addition, as illustrated inFIG.7, for example, the diode module4D′ has the disposed breakage prevention structure6D′ that covers the entire front face, which has the smaller area than the top face11, and the breakage prevention structure6D′ becomes protrusive from the top face11of the module case10of the diode module4D′ as with the breakage prevention structure6D described in the above third embodiment. The noncounter faces, including the top face11, are where no breakage prevention structures6D′ are disposed. In this case, destruction can be easily directed to the top face11with the largest area among the exterior wall faces of the module case10, and during the destruction of the diode module4D′, broken pieces scattering from the top face11of the module case10can be further prevented from scattering out of the converter101.

In the above-described first embodiment, the noncounter placement face (top face11), which is the noncounter face with the largest area among the exterior wall faces of the module case10of each of the diode modules4A and4B, has been described to be where the breakage prevention structure6A or6B is disposed and have at least the portion of the area farther from the placement face (first face)15than the middle of the noncounter placement face is as the nonplacement area7A or7B. However, as long as each of the breakage prevention structures6A and6B is disposed so that the noncounter placement face, which has the largest area among the noncounter faces included in the exterior wall faces of the module case10, includes at least the portion of the area, which is farther from the first face than the middle of the noncounter placement face is, as the nonplacement area7A or7B, any faces other than the noncounter placement face among the exterior wall faces of the module case10may also be where the breakage prevention structures6A or6B are disposed. For example, in the case of the diode module4A or4B that has the disposed breakage prevention structure6A or6B on the noncounter placement face, which is the noncounter face with the largest area among the exterior wall faces of the module case10, in addition to having at least the portion of the area farther from the first face than the middle of the noncounter placement face is as the nonplacement area7A or7B, the diode module4A or4B may have the above-described breakage prevention structure6C′ or6D′ disposed so that the front face (counter face), which has a smaller area than the top face and faces the placement face (first face)15for the body case slits2of the converter101, is entirely covered. In that case, the diode module4A or4B can direct destruction to the nonplacement area7A or7B as described in the first embodiment and make the counter face, which faces the placement face15for the body case slits2of the converter101, difficult to destroy. In addition, the converter101allows for even enhanced maintenance of reliability of equipment disposed externally to the converter101despite the destruction of the diode module4A or4B.

In the above-described third embodiment, the diode module4D has been described to have the disposed breakage prevention structure6D that covers the entire front face12of the module case10and becomes protrusive from the top face11of the module case10. However, the breakage prevention structure6D′ disposed on the front face12of the module case10only has to cover the entire front face, which is the counter face, at a face that includes an area in contact with the counter face and has a larger area than the counter face. For example, the diode module4D′ may be configured to have a disposed breakage prevention structure6D′ that covers the entire front face12of the module case10and becomes protrusive from the top face11and the two side faces of the module case10. In that case, even when destruction is directed to any of noncounter faces where no breakage prevention structures6D′ are disposed, broken pieces scattering from the diode module4D′ can be further prevented from scattering out of the converter101during the destruction of the diode module4D′.

The above configurations illustrated in the embodiments are illustrative, can be combined with other techniques that are publicly known, and can be partly omitted or changed without departing from the gist. The embodiments can be combined with each other.

REFERENCE SIGNS LIST

1body case;2body case slit;3cooling fin;4,4A to4D,4C′,4D′ diode module;5reference point;6A to6D,6C′,6D′ breakage prevention structure;7A,7B nonplacement area;10module case;11top face;12front face;13right side face;15placement face;20vertex;101converter.