JP7238635B2 - Power converter and cooling system - Google Patents

Description

The present invention relates to power converters and cooling systems.

For example, a vehicle such as a hybrid vehicle or an electric vehicle is equipped with a power conversion device that performs power conversion between DC power and AC power. A power conversion device includes electronic components for power conversion and a cooler for cooling the electronic components. In order to improve the efficiency of cooling the electronic components, this type of power conversion device may be configured to cool the electronic components using boiling heat transfer.

For example, in Patent Document 1, a first conductor and a second conductor exhibiting a rectangular parallelepiped shape, a first semiconductor element and a second semiconductor element sandwiched between the first conductor and the second conductor, A power conversion device is described that includes a heat-dissipating metal plate on which a first conductor and a second conductor are placed, and a cooler that includes a cooling block joined to the heat-dissipating metal plate. The cooling block has a rectangular recess, an annular engaging groove surrounding the recess, and a joint surface formed between the recess and the engaging groove. The recesses and engagement grooves of the cooling block are covered with a metal plate for heat dissipation.

A coolant channel in this power conversion device is composed of a space surrounded by a metal plate for heat radiation and the inner surface of the recess. Further, a sealing material is arranged in the engagement groove to seal the periphery of the coolant flow path and prevent leakage of the coolant.

JP 2015-53775 A

When trying to cool an electronic component by utilizing boiling heat transfer as in the power conversion device of Patent Document 1, it is necessary to evaporate the liquid coolant in contact with the metal plate for heat dissipation. At this time, if the coolant in contact with the metal plate for heat dissipation evaporates violently, a phenomenon called dryout occurs in which the surface of the metal plate for heat dissipation is covered with the vaporized coolant, resulting in a decrease in the cooling efficiency of electronic components.

In the conventional power conversion device, the occurrence of dryout has not become obvious because the refrigerant vaporized by contact with the heat-dissipating metal plate is swept away by the liquid refrigerant. However, in recent years, the amount of heat generated from electronic components tends to increase more and more as the output of power converters increases. As a result of detailed studies by the inventors, in such a situation, for example, the refrigerant staying in a portion where the flow velocity is relatively slow, such as between the joint surface of the cooling block and the metal plate for heat dissipation, evaporates, and the width of the refrigerant flow path is reduced. It became clear that dryout tends to occur at the ends of the direction.

In order to suppress the occurrence of dryout, for example, a method of suppressing the temperature rise at the end portions in the width direction of the coolant channel by widening the width of the coolant channel is conceivable. However, when the width of the coolant flow path increases, the flow rate of the coolant required to maintain the cooling efficiency increases, which may lead to an increase in pressure loss.

The present invention has been made in view of such problems, and aims to provide a power conversion device capable of suppressing an increase in pressure loss and suppressing the occurrence of dryout, and a cooling system equipped with this power conversion device. It is something to do.

One aspect of the present invention includes a refrigerant inlet (51, 513) into which a refrigerant is introduced, a refrigerant outlet (53, 533) connected to the refrigerant inlet and through which the refrigerant is discharged, the refrigerant inlet and the refrigerant. a cooler (2, 202-204) having a coolant flow path (5, 502-504) with a cooling opening (52) positioned between the outlet;
a component holding plate (3) stacked on the cooler and closing the cooling opening;
an electronic component (4) held on the outer surface of the component holding plate;
The coolant channel is
A component projection plane (21) formed by projecting the electronic component onto the inner surface of the cooler in the stacking direction (Z) of the cooler and the component holding plate, and a back surface of the electronic component on the component holding plate ( 31) and the component back area (54), which is the space between
and a part peripheral area (55) that is an area other than the part back area,
In a cross section perpendicular to the flow direction (X) of the coolant and passing through the electronic component, the average flow velocity of the coolant in the component rear region is configured to be higher than the average flow velocity of the coolant in the component peripheral region. , in the power converters (1, 102-104).

Another aspect of the present invention is the power conversion device of the above aspect, a refrigerant flowing in the refrigerant flow path of the power conversion device, and a refrigerant circulation device (7) connected to the refrigerant flow path and configured to circulate the refrigerant. ) in a cooling system (10) comprising:

The power conversion device includes a cooler having a coolant channel, a component holding plate that closes the cooling opening of the coolant channel, and an electronic component held on the outer surface of the component holding plate, The component holding plate is configured to cool the electronic component by contacting the cooling medium with the component holding plate. Further, the coolant flow path has the component back area and a component peripheral area that is an area other than the component back area. In a cross section passing through the electronic component, the average flow velocity of the coolant in the component back area is configured to be higher than the average flow velocity of the coolant in the component peripheral area.

In this way, by making the average flow velocity of the coolant in the component back area higher than that in the component peripheral area, it is possible to efficiently cool the back surface of the electronic component on the component holding plate, to which heat from the electronic component is most easily transmitted. . In addition, by flowing the coolant around the component, air bubbles of the coolant can be washed away and the occurrence of dryout can be suppressed. Furthermore, by making the average flow velocity of the coolant in the component peripheral region smaller than that in the component rear region, it is possible to suppress an increase in the flow rate of the coolant and, in turn, to suppress an increase in pressure loss.

As described above, according to the above aspect, it is possible to provide a power converter that can suppress an increase in pressure loss and suppress the occurrence of dryout, and a cooling system that includes this power converter.
It should be noted that the symbols in parentheses described in the claims and the means for solving the problems indicate the corresponding relationship with the specific means described in the embodiments described later, and limit the technical scope of the present invention. not a thing

FIG. 1 is a perspective view of a power converter according to Embodiment 1. FIG. FIG. 2 is a top view of the power converter according to Embodiment 1. FIG. 3 is a cross-sectional view taken along the line III--III in FIG. 2. FIG. 4 is a perspective view of a cooler according to Embodiment 1. FIG. FIG. 5 is a cross-sectional view showing a main part of a power conversion device in which a protruded streak portion is provided in a sub-channel portion according to Embodiment 2. FIG. FIG. 6 is a perspective view of a cooler according to Embodiment 2. FIG. FIG. 7 is a top view of a cooler in which a sub-channel part is provided in part of the coolant channel according to the third embodiment. 8 is a cross-sectional view taken along line VIII--VIII of FIG. 7. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 7. FIG. FIG. 10 is a top view of a cooler in which the width of the sub-flow path portion increases from the coolant inlet toward the coolant outlet according to the fourth embodiment. FIG. 11 is an explanatory diagram showing a schematic configuration of a cooling system according to the fifth embodiment. FIG. 12 is an explanatory diagram showing the flow velocity distribution of the specimen S1 in the experimental example. FIG. 13 is an explanatory diagram showing the flow velocity distribution of the specimen S2 in the experimental example. FIG. 14 is an explanatory diagram showing calculation results of thermal resistance in an experimental example.

(Embodiment 1)
An embodiment of the power converter will be described with reference to FIGS. 1 to 4. FIG. The power converter 1 of this embodiment has a cooler 2, a component holding plate 3, and electronic components 4, as shown in FIGS. As shown in FIGS. 3 and 4, the cooler 2 includes a refrigerant inlet 51 through which the refrigerant is introduced, a refrigerant outlet 53 connected to the refrigerant inlet 51 and through which the refrigerant is discharged, the refrigerant inlet 51 and the refrigerant outlet. a cooling opening 52 positioned between the outlet 53 and the coolant flow path 5 . As shown in FIG. 3 , the component holding plate 3 is laminated on the cooler 2 . Also, the cooling opening 52 of the cooler 2 is closed by the component holding plate 3 . The electronic component 4 is held on the outer surface of the component holding plate 3 .

The cooling medium flow path 5 includes a component projection plane 21 formed by projecting the electronic component 4 onto the inner surface of the cooler 2 in the stacking direction of the cooler 2 and the component holding plate 3, and a back surface of the electronic component 4 on the component holding plate 3. 31 and a component peripheral area 55 other than the component back area 54 . In addition, the coolant flow path 5 is arranged so that the average flow velocity of the coolant in the component rear area 54 is higher than the average flow velocity of the coolant in the component peripheral area 55 in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4 . is configured to

The configuration of the power converter 1 of this embodiment will be described in more detail below. The cooler 2 of this embodiment includes a rectangular parallelepiped flow path forming portion 22 as shown in FIG. 1, a coolant flow path 5 passing through the flow path forming portion 22 as shown in FIGS. have. As shown in FIG. 4 , a coolant introduction port 51 is opened at one end surface 221 in the longitudinal direction of the flow path forming portion 22 , and a coolant outlet port 53 is opened at the other end surface 222 .

Between the end face 221 having the coolant inlet port 51 and the end face 222 having the coolant outlet port 53, there are a top face 223 having the cooling openings 52, a bottom face 224 located on the opposite side of the top face 223, There are two side surfaces 225 connecting the surface 223 and the bottom surface 224 . The flow path forming portion 22 may be made of metal such as aluminum, for example.

In the following description, the direction parallel to the flow direction of the coolant is the “vertical direction X”, the direction in which the two side surfaces 225 are arranged in the flow path forming portion 22 is the “horizontal direction Y”, and the lamination of the cooler 2 and the component holding plate 3 The direction may be referred to as "stacking direction Z". In addition, the top surface 223 side in the stacking direction Z may be referred to as "upper Z1", and the bottom surface 224 side may be referred to as "lower Z2". These orientation indications are for the sake of convenience, and have nothing to do with the orientation when the power conversion device 1 is attached to a vehicle or the like.

As shown in FIG. 4 , the cooling openings 52 of this embodiment extend over the entire longitudinal direction X in the flow path forming portion 22 . Note that the shape of the cooler 2 and the arrangement of the coolant flow paths 5 in the flow path forming portion 22 are not limited to the mode of this embodiment.

Further, the top surface 223 of the flow path forming portion 22 of this embodiment has grooves 226 arranged outside the cooling openings 52 in the horizontal direction Y. As shown in FIG. Inside the groove 226, a sealing material 6, which will be described later, is accommodated.

As shown in FIGS. 1 and 2 , the component holding plate 3 is arranged on the top surface 223 of the flow path forming portion 22 . The component holding plate 3 may be made of, for example, metal having high thermal conductivity such as copper or aluminum, or may be made of electrically insulating ceramics having high thermal conductivity such as alumina, aluminum nitride, or silicon nitride. may be configured.

As shown in FIG. 3, the component holding plate 3 of this embodiment includes an insulating substrate 33 made of ceramics and arranged on the top surface 223 of the flow path forming portion 22, and an insulating substrate 33 made of a conductor and laminated above the insulating substrate 33 Z1. and a circuit pattern portion 34 . The insulating substrate 33 is arranged so as to cover the cooling openings 52 and the grooves 226 of the flow path forming portion 22 . Although not shown, a minute gap is formed between the insulating substrate 33 and the top surface 223 of the flow path forming portion 22 .

The component holding plate 3 is attached to the cooler 2 so as to close the cooling opening 52 and prevent leakage of the coolant flowing through the coolant channel 5 . The component holding plate 3 may be attached in any manner as long as it can close the cooling openings 52 and prevent leakage of the coolant. For example, the component holding plate 3 may be joined to the flow path forming portion 22 via a metal sintered body obtained by sintering fine metal particles such as Si or a joining material such as wax.

Further, the component holding plate 3 can be attached to the flow channel forming portion 22 with a sealing material 6 such as an O-ring or a liquid gasket interposed between the component holding plate 3 and the flow channel forming portion 22 . In this case, the sealing material 6 sandwiched between the component holding plate 3 and the flow path forming portion 22 seals the two in a liquid-tight manner, thereby preventing leakage of the coolant.

In this embodiment, as shown in FIG. 3, an O-ring as a sealing material 6 is arranged between the insulating substrate 33 of the component holding plate 3 and the groove 226 of the flow path forming portion 22 . The sealing material 6 is sandwiched between the inner surface of the groove 226 and the component holding plate 3 . As a result, the space between the flow path forming portion 22 and the component holding plate 3 is liquid-tightly sealed.

An electronic component 4 is held on the circuit pattern portion 34 of the component holding plate 3 . As the electronic component 4, for example, a semiconductor switching element such as a field effect transistor or an insulated gate bipolar transistor, a semiconductor rectifying element such as a freewheel diode, or the like can be used. These elements may include, for example, semiconductors such as silicon semiconductors and silicon carbide semiconductors. Specifically, the electronic component 4 of this embodiment is a switching element including a silicon carbide semiconductor. Further, in this embodiment, one electronic component 4 is held on the circuit pattern portion 34, but a plurality of electronic components 4 may be held on the circuit pattern portion 34 at one location.

The electronic component 4 may be joined to the circuit pattern portion 34 via a conductive joining material such as solder. Although not shown in the drawings, the electronic component 4 of this embodiment is bonded to the circuit pattern portion 34 via solder as a bonding material.

A coolant channel 5 in the power converter 1 is configured by a space surrounded by the channel forming portion 22 of the cooler 2 and the component holding plate 3 . The coolant flow path 5 includes a component projection surface 21 formed by projecting the electronic component 4 onto the inner surface of the cooler 2 in the stacking direction Z (that is, the vertical direction) of the cooler 2 and the component holding plate 3, and the component holding plate. 3 and a component peripheral region 55 that is a region other than the component back region 54 . The coolant flow path 5 is configured so that the average flow velocity of the coolant in the component back area 54 is higher than the average flow velocity of the coolant in the component peripheral area 55 in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4. If so, it can take various forms.

For example, the coolant channel 5 is perpendicular to the flow direction of the coolant, and the channel cross-sectional area of the component peripheral region 55 in the cross section passing through the electronic component 4 is smaller than the channel cross-sectional area of the component rear region 54. may be configured. In this case, the coolant supplied from the coolant introduction port 51 easily flows into the component rear region 54 having a larger channel cross-sectional area and a lower pipeline resistance than the component peripheral region 55 . As a result, the average flow velocity of the coolant in the component back area 54 is made higher than the average flow velocity of the coolant in the component peripheral area 55, thereby suppressing an increase in pressure loss and the occurrence of dryout.

Specifically, the coolant flow path 5 of the above aspect has a semicircular shape, a V shape, a T shape, or the like in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4. A coolant channel 5 is included having a shape in which the depth of the channel 5 is not uniform. By arranging the component back area 54 so as to include the deepest portion of the coolant channel 5 in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4, the above-described effects can be achieved. can be done.

The coolant channel 5 has a main channel portion 56 which is perpendicular to the flow direction of the coolant and has a rectangular cross section passing through the electronic component 4, and a portion extending from the main channel portion 56 to the cooler 2 and the component holding plate 3. A secondary channel portion 57 extending in a direction perpendicular to the stacking direction and having a channel cross-sectional area smaller than that of the main channel portion 56 may be provided, and the component back surface region 54 may be arranged in the main channel portion 56 . In this case, similarly to the above, the coolant supplied from the coolant introduction port 51 can easily flow into the main channel portion 56 having a larger channel cross-sectional area and a smaller channel resistance. Therefore, by arranging the component back area 54 in the main channel portion 56 , the average flow velocity of the coolant in the component back area 54 can be made higher than the average flow velocity of the coolant in the component peripheral area 55 . As a result, it is possible to suppress an increase in pressure loss and suppress the occurrence of dryout.

The coolant channel 5 in this embodiment has a constant cross-sectional shape over the entire length in the vertical direction X. As shown in FIG. More specifically, as shown in FIG. 3, the coolant channel 5 extends outward in the width direction from the main channel portion 56 and the upper end of the main channel portion 56 in a cross section perpendicular to the flow direction of the coolant. It has a T-shaped cross-sectional shape with two secondary flow passage portions 57 .

Further, the component peripheral region 55 of this embodiment continues to the gap (not shown) between the top surface 223 of the cooler 2 and the component holding plate 3 . As a result, air bubbles generated from the gap between the top surface 223 of the cooler 2 and the component holding plate 3 are quickly washed away by the refrigerant, and the occurrence of dryout can be suppressed more effectively.

The average flow velocity of the coolant in the component back area 54 can be calculated by the following method. First, a fluid analysis is performed by the Zero Equation & k-Omega method to calculate the flow rate distribution of the coolant in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4 . The average flow velocity of the coolant in the component back area 54 can be obtained by dividing the flow rate of the coolant flowing in the component back area 54 based on the analysis result by the cross-sectional area of the flow path of the component back area 54 . Note that the channel cross-sectional area of the component back area 54 in this embodiment is specifically the cross-sectional area of the component back area 54 in a cross section perpendicular to the longitudinal direction X. As shown in FIG.

Also, the average flow velocity of the coolant in the component peripheral region 55 can be calculated by a method similar to that for the average flow velocity of the coolant in the component rear region 54 . That is, the fluid analysis is performed by the Zero Equation & k-Omega method, and the flow rate distribution of the coolant in the cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4 is calculated. The average flow velocity of the coolant in the component peripheral region 55 can be obtained by dividing the flow rate of the coolant flowing in the component peripheral region 55 obtained based on the analysis result by the flow passage cross-sectional area of the component peripheral region 55 . Note that the channel cross-sectional area of the component peripheral region 55 in this embodiment is specifically the cross-sectional area of the component peripheral region 55 in a cross section orthogonal to the longitudinal direction X. As shown in FIG.

The average coolant flow velocity in the component back area 54 is greater than 1.0 times the average coolant flow velocity in the component peripheral area 55 . From the viewpoint of further increasing the cooling efficiency of the electronic component, the average flow velocity of the coolant in the component rear area 54 is preferably 2.0 times or more, and preferably 3.0 times or more, the average flow velocity of the coolant in the component peripheral area 55. It is more preferable to have

In addition, from the viewpoint of suppressing an increase in pressure loss, the average flow velocity of the refrigerant in the component rear area 54 is preferably 5.0 times or less, and 4.0 times or less, the average flow velocity of the refrigerant in the component peripheral area 55. is more preferably 3.0 times or less.

Next, the effect of this form is demonstrated. The power conversion device 1 includes a cooler 2 having a coolant channel 5, a component holding plate 3 closing a cooling opening 52 of the coolant channel 5, and an electronic component 4 held on the outer surface of the component holding plate 3. , so that the component holding plate 3 is brought into contact with the cooling medium to cool the electronic component 4 . Further, the coolant channel 5 has a component back area 54 and a component peripheral area 55 that is an area other than the component back area 54 . In the power conversion device 1, the average flow velocity of the coolant in the component back area 54 is higher than the average flow velocity of the coolant in the component peripheral area 55 in a cross section perpendicular to the flow direction of the coolant and passing through the electronic component 4. is configured to

In this manner, by making the average flow velocity of the coolant in the component back area 54 higher than that in the component peripheral area 55, the back surface of the electronic component 4 on the component holding plate 3, to which the heat from the electronic component 4 is most likely to be transmitted, is efficiently cooled. can do. In addition, by flowing the coolant in the component peripheral region 55, it is possible to wash away the bubbles of the coolant and suppress the occurrence of dryout. Furthermore, by making the average flow velocity of the coolant in the component peripheral region 55 lower than that in the component rear region 54, it is possible to suppress an increase in the flow rate of the coolant and, in turn, an increase in pressure loss.

As described above, according to the present embodiment, it is possible to provide the power converter 1 that can suppress the increase in pressure loss and suppress the occurrence of dryout.

(Embodiment 2)
As shown in FIG. 5, the coolant channel 502 in the power conversion device 102 of this embodiment has a main channel portion 56 and a sub-channel portion 58, and a projecting portion 581 is formed in the sub-channel portion 58. is provided. Note that, of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the previous embodiments represent the same components as those in the previous embodiments, unless otherwise specified.

A power converter 102 of this embodiment has a cooler 202 , a component holding plate 3 , and electronic components 4 . The cooler 202 has a coolant channel 502 having a coolant inlet 51 (not shown), a cooling opening 52, and a coolant outlet 53 (not shown). The coolant flow path 502 of this example has a component back area 54 and a component peripheral area 55 that is an area other than the component back area 54 , is perpendicular to the flow direction of the coolant, and allows the electronic component 4 to pass through. The average flow velocity of the coolant in the component rear region 54 is higher than the average flow velocity of the coolant in the component peripheral region 55 in a cross section passing through.

The coolant channel 502 has a main channel portion 56 that is perpendicular to the flow direction of the coolant and has a rectangular cross section passing through the electronic component 4 , and a portion extending from the main channel portion 56 to the cooler 202 and the component holding plate 3 . and a secondary channel portion 58 extending in a direction perpendicular to the stacking direction and having a channel cross-sectional area smaller than that of the main channel portion 56 . The component back area 54 of this embodiment is arranged in the main flow passage portion 56 .

The secondary flow path portion 58 extends outward in the width direction from the upper end of the main flow path portion 56 . In addition, a plurality of projecting portions 581 projecting upward Z<b>1 from the inner surface of the flow path forming portion 22 are provided in the sub flow path portion 58 . As shown in FIG. 6, the protrusions 581 have a plate shape extending in the vertical direction X (that is, the flow direction of the coolant) and are arranged in the horizontal direction Y at intervals. Further, as shown in FIG. 5, there is a gap between the upper end of the projecting portion 581 and the component holding plate 3, the gap being large enough for the coolant to flow.

By providing the projecting portion 581 in the secondary flow channel portion 58 as in this embodiment, the pipeline resistance in the secondary flow channel portion 58 can be further increased. As a result, the average flow velocity of the coolant flowing through the sub-flow path portion 58 can be further reduced, and the average flow velocity of the coolant flowing through the component peripheral region 55 can be further reduced. As a result, the average flow velocity of the coolant in the component back area 54 can be further increased, and the cooling efficiency of the electronic component 4 can be further improved. In addition, the power conversion device 102 of this embodiment can achieve the same effects as those of the first embodiment.

It should be noted that the arrangement and shape of the protrusion 581 can take various forms other than the form of this embodiment. For example, the projections 581 may have a columnar shape such as a columnar shape or a prismatic shape, and may be interspersed within the sub-channel portion 58 . Also, the projecting portion 581 may have a plate shape extending in a direction other than the vertical direction X, such as in the horizontal direction Y or in a direction oblique to the vertical direction X.

(Embodiment 3)
The power conversion device 103 of this embodiment includes a cooler 203, a component holding plate 3, and electronic components 4, which are not shown in the drawing. The cooler 203 has a coolant channel 503 having a coolant inlet 51 , a cooling opening 52 , and a coolant outlet 53 , as shown in FIG. 7 .

As shown in FIG. 8, the coolant introduction port 513 in the coolant channel 503 has a rectangular shape in a cross section perpendicular to the flow direction of the coolant. Although not shown, the coolant outlet port 533 has a rectangular cross section perpendicular to the flow direction of the coolant, like the coolant inlet port 513 .

9, the portion between the coolant inlet port 513 and the coolant outlet port 533 in the coolant channel 503 has a T-shaped cross section including a main channel portion 56 and a secondary channel portion 57. have a shape. Further, as shown in FIG. 7, the total width of the main flow path portion 56 and the width of the sub flow path portion 57 in the horizontal direction Y is the same as the width of the coolant inlet 513 and the width of the coolant outlet 533 . Others are the same as those of the first embodiment.

As can be understood from a comparison between FIG. 8 and FIG. 9, in the refrigerant flow path 503 of this embodiment, the flow path cross-sectional area of the refrigerant inlet port 513 and the refrigerant outlet port 533 in the cross section perpendicular to the flow direction of the refrigerant is It is configured to be larger than the sum of the channel cross-sectional area of the component peripheral region 55 and the channel cross-sectional area of the component rear region 54 in a cross section perpendicular to the flow direction and passing through the electronic component 4 . This can further reduce the pressure loss when the coolant is supplied from the coolant introduction port 513 . As a result, the cooling efficiency of the electronic component 4 can be further enhanced. In addition, the power conversion device 103 of this embodiment can achieve the same effects as those of the first embodiment.

(Embodiment 4)
A power converter 104 of this embodiment has a cooler 204, a component holding plate 3, and two electronic components 4 shown in FIG. The two electronic components 4 are spaced apart from each other in the longitudinal direction X. As shown in FIG. The cooler 204 also has a coolant channel 504 having a coolant inlet 51 , a cooling opening 52 , and a coolant outlet 53 .

The coolant channel 504 of this embodiment has a T-shaped cross-sectional shape including a main channel portion 56 and a secondary channel portion 59 over the entire length from the coolant inlet port 51 to the coolant outlet port 53 . The secondary channel portion 59 is configured such that the width thereof is the narrowest at the refrigerant inlet 51 and the width becomes narrower toward the refrigerant outlet 53 side. Others are the same as those of the first embodiment.

When a plurality of electronic components 4 are arranged along the flow direction of the coolant as in this embodiment, the upstream electronic components 4a are cooled by the relatively low-temperature coolant. On the other hand, since the downstream electronic component 4b exchanges heat with the coolant whose temperature has been raised by the heat exchange with the upstream electronic component 4b, the cooling efficiency tends to decrease compared to the upstream electronic component 4a.

On the other hand, the coolant channel 504 of this embodiment is configured such that the cross-sectional area of the coolant channel in the flow direction of the coolant becomes smaller as it approaches the coolant outlet port 53 . As a result, the flow velocity of the coolant can be increased as it approaches the coolant outlet port 53 . As a result, the cooling efficiency of the electronic component 4b on the downstream side can be further improved. In addition, the power conversion device 104 of this embodiment can achieve the same effects as those of the first embodiment.

(Embodiment 5)
In this embodiment, a cooling system 10 including a power conversion device 1, a coolant flowing through a coolant flow path 5 of the power conversion device 1, and a coolant circulation device 7 that circulates the coolant in the power conversion device 1 will be described. For example, as shown in FIG. 11, the refrigerant circulation device 7 connects a pump 71 for flowing the refrigerant, the pump 71 and the refrigerant inlet port 51, and the pump 71 and the refrigerant outlet port 53. It has a pipe 72 . The refrigerant circulation device 7 may further include a heat exchanger 73 such as a radiator that exchanges heat between the refrigerant and the outside air.

As the coolant circulated in the cooling system 10, for example, water, long-life coolant, or the like can be used. The cooling system 10 of this embodiment is configured to be able to supply a long-life coolant as a coolant into the coolant channel 5 at a maximum pressure of 2 MPa. In addition, when the electronic component 4 is operating at the rated output, the pressure of the refrigerant is about 0.2 MPa, and the flow rate is about 10 L/min.

In the cooling system 10 of this embodiment, the average flow velocity of the coolant in the component rear region 54 is 3.0 m/s or more, and the average flow velocity of the coolant in the component peripheral region 55 is 1.5 m/s or less. is configured to Further, the cooling system 10 of this embodiment is configured so that the flow of the coolant in the component back area 54 can be turbulent and the flow of the coolant in the component peripheral area 55 can be laminar.

Therefore, the cooling system 10 of this embodiment can efficiently cool the back surface of the electronic component 4 on the component holding plate 3 . In addition, the cooling system 10 of this embodiment can quickly wash away air bubbles generated by vaporization of the refrigerant. Furthermore, by making the average flow velocity of the coolant in the component peripheral region 55 smaller than that in the component rear region 54, it is possible to suppress an increase in the flow rate of the coolant and, in turn, to suppress an increase in pressure loss. As a result, it is possible to suppress an increase in pressure loss and suppress the occurrence of dryout.

The cooling system of this embodiment can effectively suppress the occurrence of dryout particularly in applications where the maximum amount of heat generated from the electronic component 4 is 250 W or more. Such applications include, for example, cooling systems for switching elements comprising silicon carbide semiconductors.

(Experimental example)
In order to confirm the effects of the coolant flow path 5 in Embodiment 1, simulations and experiments were performed as follows. The structures of the specimens S1 and S2 used in this example are described below. The test bodies S1 and S2 simulate the cooler 2 in the first embodiment.

・ Specimen S1
The specimen S1 has external dimensions of 100 mm long, 100 mm wide and 100 mm high. In addition, the specimen S1 has a coolant channel 5 extending over the entire length in the vertical direction. The coolant flow path 5 has a T-shaped cross section having a main flow path portion 56 and a sub flow path portion 57 in a cross section orthogonal to the longitudinal direction. The main channel portion 56 has a width of 12 mm and a depth of 3 mm. Moreover, the width of the sub flow path portion 57 is 3 mm, and the depth thereof is 1 mm.

・ Specimen S2
The specimen S2 has external dimensions of 100 mm long, 100 mm wide and 100 mm high. Moreover, the test body S2 has a coolant channel 5 extending over the entire length in the vertical direction. The coolant channel 5 has a rectangular shape with a width of 18 mm and a depth of 3 mm in a cross section perpendicular to the longitudinal direction.

In addition, a transparent window is provided on the bottom surface 224 of each specimen so that the presence or absence of air bubbles can be visually observed. Further, the electronic component 4 was arranged at a position where the distance from the end of the coolant channel 5 in the width direction was 9 mm and the distance from the coolant outlet port 53 was 50 mm.

・Simulation Structural models of the specimens S1 and S2 were prepared, and the flow velocity distribution of the coolant flowing through the coolant passage 5 was calculated by thermal fluid analysis using the Zero Equation & k-Omega method. The temperature of the coolant was set to 60° C., and the amount of heat generated by the electronic component 4 was set to 450W. FIG. 12 shows the flow velocity distribution of the refrigerant flowing through the test body S1 when the flow rate of the refrigerant supplied from the refrigerant inlet 51 is 15 L/min. Further, FIG. 13 shows the flow velocity distribution of the refrigerant flowing through the test body S2 when the flow rate of the refrigerant supplied from the refrigerant inlet 51 is 15 L/min. 12 and 13 are diagrams showing the flow velocity distribution in a cross section at a distance of 100 μm downward from the component holding plate 3. FIG.

As shown in FIG. 12, the flow velocity of the refrigerant flowing from the refrigerant inlet 51 in the specimen S1 tends to increase toward the refrigerant outlet 53 side. Further, when comparing the flow velocity of the coolant in the main channel portion 56 and the flow velocity of the coolant in the sub-channel portion 57 in the cross section where the position in the vertical direction X is the same, the flow velocity of the coolant in the main channel portion 56 is the same as that in the sub-channel. It can be seen that the flow velocity of the coolant in the portion 57 tends to be greater. In the test specimen S1 of this example, the average flow velocity of the coolant in the component back area 54 can be set to 3.0 m/s or more, and the average flow velocity of the coolant in the component peripheral area 55 can be set to 1.5 m/s or less. rice field.

On the other hand, as shown in FIG. 13, in the specimen S2 that does not have the sub-channel portion 57, the change in the flow velocity of the refrigerant in the refrigerant passage 5 is smaller than that in the specimen S1, and the refrigerant flows uniformly. I understand that there are In addition, it can be understood that the flow velocity of the coolant at both ends in the width direction of the coolant channel 5 tends to be higher than the flow velocity of the coolant at the center in the test body S2. In the test specimen S2 of this example, the average flow velocity of the coolant in the component back area 54 was lower than the average flow velocity of the coolant in the component peripheral area 55 . The average flow velocity of the coolant in the component back area 54 and the average flow velocity of the coolant in the component peripheral area 55 of the specimen S2 were both about 2 m/s.

Furthermore, in the thermal fluid analysis described above, the thermal resistance from the electronic component 4 to the coolant was calculated in a steady state, that is, when the temperature of the electronic component 4 reached a certain temperature. FIG. 14 shows the thermal resistance values of the specimens S1 and S2 when the coolant flow rate is varied. 14 is the thermal resistance of the component holding plate 3, that is, the value obtained by dividing the temperature difference between the electronic component 4 and the coolant by the amount of heat generated, and the horizontal axis is the amount of coolant supplied from the coolant inlet 51. is the flow rate.

As shown in FIG. 14, the test body S1 can achieve the same thermal resistance as that of the test body S2 while reducing the refrigerant flow rate more than that of the test body S2.

- Experiment Next, the presence or absence of dry-out was evaluated when the electronic component 4 was cooled by flowing a coolant through the coolant channels 5 of the test bodies S1 and S2. Specifically, water was supplied as a coolant into the coolant channels 5 of the test bodies S1 and S2. In addition, the temperature of the refrigerant|coolant was 60 degreeC. Also, the flow rate of the refrigerant supplied from the refrigerant inlet 51 was set to 15 L/min.

Then, the electronic component 4 was caused to generate heat while flowing the coolant through the coolant channel 5, and the presence or absence of the generation of air bubbles was visually observed. The amount of heat generated by the electronic component 4 was set to 450W.

In the test sample S1, it was possible to quickly wash away the air bubbles generated in the coolant channel 5 and suppress the occurrence of dryout. On the other hand, in the test sample S2, bubbles grew at both ends of the coolant channel 5 in the width direction, and dryout occurred.

From these results, it can be easily understood that the occurrence of dryout can be suppressed by making the average flow velocity of the coolant in the component rear region 54 higher than the average flow velocity of the coolant in the component peripheral region 55 .

The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention.

Reference Signs List 1, 102-104 power conversion device 2, 202-204 cooler 21 component projection surface 3 component holding plate 31 rear surface 4 electronic component 5, 502-504 refrigerant flow path 51 refrigerant inlet port 52 cooling opening 53 refrigerant outlet port 54 component rear surface Area 55 Part peripheral area

Claims (7)

A refrigerant inlet (51, 513) into which a refrigerant is introduced, a refrigerant outlet (53, 533) connected to the refrigerant inlet and through which the refrigerant is discharged, and arranged between the refrigerant inlet and the refrigerant outlet. a cooler (2, 202-204) having a coolant flow path (5, 502-504) with a cooled cooling opening (52);
a component holding plate (3) stacked on the cooler and closing the cooling opening;
an electronic component (4) held on the outer surface of the component holding plate;
The coolant channel is
A component projection plane (21) formed by projecting the electronic component onto the inner surface of the cooler in the stacking direction (Z) of the cooler and the component holding plate, and a back surface of the electronic component on the component holding plate ( 31) and the component back area (54), which is the space between
and a part peripheral area (55) that is an area other than the part back area,
In a cross section perpendicular to the flow direction (X) of the coolant and passing through the electronic component, the average flow velocity of the coolant in the component rear region is configured to be higher than the average flow velocity of the coolant in the component peripheral region. , power converters (1, 102-104). 2. The power conversion device according to claim 1, wherein a flow path cross-sectional area of said component peripheral region in a cross section perpendicular to a coolant flow direction and passing through said electronic component is smaller than a flow channel cross-sectional area of said component rear region. The coolant channel has a main channel portion (56) which is perpendicular to the flow direction of the coolant and has a rectangular cross section passing through the electronic component, and a main channel portion (56) extending from the main channel portion to the cooler and the component holding plate. sub-channel portions (57 to 59) extending in a direction perpendicular to the stacking direction and having a channel cross-sectional area smaller than that of the main channel portion; 3. The power conversion device according to claim 1 or 2, wherein: The cross-sectional area of the coolant inlet (513) and the coolant outlet (533) in the cross section perpendicular to the flow direction of the coolant is the part in the cross section perpendicular to the coolant flow direction and passing through the electronic component. The power conversion device (103) according to any one of claims 1 to 3, wherein the power converter (103) is larger than the sum of the channel cross-sectional area of the peripheral area and the channel cross-sectional area of the component back area. The power converter according to any one of claims 1 to 4, a refrigerant flowing in the refrigerant flow path of the power converter, and a refrigerant circulation device connected to the refrigerant flow path and circulating the refrigerant ( 7) and a cooling system (10). The average flow velocity of the coolant in the part back area is 3.0 m/s or more, and the average flow velocity of the coolant in the part peripheral area is 1.5 m/s or less. 6. A cooling system (10) according to claim 5. 7. The cooling system (10) according to claim 5 or 6, wherein the cooling system (10 ).

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