JP7103275B2 - Power converter - Google Patents

Description

The techniques disclosed herein relate to power converters.

Patent Document 1 discloses a power converter in which a laminate in which a semiconductor module for power conversion and a cooler are laminated is housed in a case. In the laminated body, the cooler at one end in the stacking direction (one end in the direction in which the semiconductor module and the cooler are laminated) is in contact with the inner surface of the side wall of the case, and a load in the stacking direction is applied from the other end by a leaf spring. Has been done. Hereinafter, for convenience of explanation, the direction in which the semiconductor module and the cooler are laminated is simply referred to as the “stacking direction”.

The thickness of the portion of the side wall of the case that is in contact with the laminated body is larger than that of the other portions, and the temperature sensor is attached to that portion. The temperature sensor measures the temperature of the cooler in contact with the side wall of the case. The measured value of the temperature sensor is used as an estimated value of the temperature of the refrigerant flowing through the cooler. The flow rate of the refrigerant is adjusted based on the measured value of the temperature sensor.

Japanese Unexamined Patent Publication No. 2017-085822

In the power converter disclosed in Patent Document 1, the cooler is in contact with the inner surface of the side wall of the case. Therefore, the heat of the side wall portion in contact with the cooler is diffused throughout the case. As a result, the measured value of the temperature sensor provided on the side wall is an intermediate value between the temperature of the refrigerant flowing through the cooler and the temperature of the case, and the estimated value of the refrigerant temperature is not high in accuracy. The present specification provides a structure that can obtain a more accurate refrigerant temperature estimate.

The power converter disclosed in the present specification includes a laminated body in which a semiconductor module for power conversion and a cooler are laminated, a case accommodating the laminated body, and a support wall supporting the laminated body. It is equipped with a temperature sensor and a plate member. The support wall that supports the laminated body is in contact with the cooler at one end of the laminated body in the stacking direction in the case. The temperature sensor is mounted on the support wall. A plate member connects the side wall of the case and the support wall. The thickness of the plate member is thinner than the thickness of the support wall.

In the power converter disclosed herein, the support wall that supports the laminate and the side wall of the case are connected by a thin plate member. Therefore, heat transfer from the support wall to the side wall is suppressed as compared with the conventional power converter. Therefore, the measured value of the temperature sensor provided on the support wall is close to the temperature of the refrigerant flowing through the cooler. That is, in the power converter disclosed in the present specification, the accuracy of the estimated value of the refrigerant temperature flowing through the cooler is higher than before. Details of the techniques disclosed herein and further improvements will be described in the "Modes for Carrying Out the Invention" below.

It is a top view of the power converter of an Example. It is a top view of the case of a power converter. It is sectional drawing of the power converter along the line III-III of FIG.

The power converter 2 of the embodiment will be described with reference to the drawings. FIG. 1 shows a plan view of the power converter 2. FIG. 2 is a plan view of the power converter 2 excluding the top cover. The electric power converter 2 is a device mounted on an electric vehicle that converts the electric power of the main battery into the driving electric power of a traveling motor.

The power converter 2 houses the laminated body 20 and the sensor unit 14 in the case 10. In addition to the laminated body 20 and the sensor unit 14, various parts are housed in the case 10, but their illustrations are omitted. For convenience of explanation, the + Z direction of the coordinate system in the figure is defined as "up".

The laminated body 20 is a unit in which a plurality of semiconductor modules 3 and a plurality of coolers 4 are laminated. The semiconductor module 3 houses a semiconductor element for power conversion. A semiconductor element for power conversion is also called a power element. Specifically, the semiconductor element for power conversion is a switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). These semiconductor elements are used in voltage converters and inverters to regulate voltage and convert direct current to alternating current. Since a large current flows through these semiconductor elements, the amount of heat generated is large. Two semiconductor elements are housed in one semiconductor module 3. A power terminal extends from the upper surface of the semiconductor module 3, but its illustration is omitted. A control terminal extends from the lower surface of the semiconductor module 3. The control terminals will be described later.

The semiconductor module 3 and the cooler 4 are both flat and arranged so that their wide surfaces face each other. In the laminated body 20, the plurality of semiconductor modules 3 and the plurality of coolers 4 are laminated so that the coolers 4 are located on both sides of the respective semiconductor modules 3. In other words, a plurality of semiconductor modules 3 and a plurality of coolers 4 are alternately laminated one by one. The X direction in the coordinate system in the figure corresponds to the stacking direction of the semiconductor module 3 and the cooler 4. Hereinafter, for convenience of explanation, the stacking direction of the semiconductor module 3 and the cooler 4 is simply referred to as a “stacking direction”. In FIG. 1, a cooler at one end in the stacking direction is designated by reference numeral 4a to distinguish it from the other coolers 4. The cooler at the other end in the stacking direction is designated by reference numeral 4b to distinguish it from other coolers. However, when any one of the coolers is represented without distinction, it is referred to as the cooler 4.

The coolers 4 adjacent to each other with the semiconductor module 3 interposed therebetween are connected by connecting pipes 5a and 5b. The cooler 4 is a tube whose inside is a refrigerant flow path, and the connecting pipes 5a and 5b communicate with the refrigerant flow paths of adjacent coolers 4. The connecting tubes 5a and 5b are located on both sides of the semiconductor module 3.

A refrigerant supply pipe 6a and a refrigerant discharge pipe 6b are connected to a cooler 4a at one end in the stacking direction. When viewed from the stacking direction (X direction in the drawing), the refrigerant supply pipe 6a is located so as to overlap the connecting pipe 5a, and the refrigerant discharge pipe 6b is located so as to overlap the connecting pipe 5b. The refrigerant supply pipe 6a and the refrigerant discharge pipe 6b penetrate the side wall 18 of the case 10 and extend to the outside of the case 10. A refrigerant circulation device (not shown) is connected to the refrigerant supply pipe 6a and the refrigerant discharge pipe 6b. The refrigerant sent from the refrigerant circulation device is distributed to all the coolers 4 through the refrigerant supply pipe 6a and the connecting pipe 5a. The refrigerant flows in the cooler 4 from the connecting pipe 5a toward the connecting pipe 5b. The refrigerant absorbs the heat of the adjacent semiconductor module 3 while flowing through the cooler 4. The heat-absorbed refrigerant is returned to the refrigerant circulation device through the connecting pipe 5b and the refrigerant discharge pipe 6b. The refrigerant is water or antifreeze.

The laminated body 20 is arranged between the support wall 12 provided in the case 10 and the support column 19. A leaf spring 29 is sandwiched between the support column 19 and the laminated body 20. The center of the leaf spring 29 is in contact with the cooler 4b at one end, and each of both ends is in contact with the support column 19. The leaf spring 29 pressurizes the laminated body 20 in the laminating direction. By pressurizing the leaf spring 29, the adjacent cooler 4 and the semiconductor module 3 are brought into close contact with each other, and the efficiency of heat transfer from the semiconductor module 3 to the cooler 4 is improved. The cooler 4a at the other end of the laminate 20 is in contact with the support wall 12. The support wall 12 supports the laminated body 20 pushed by the leaf spring 29.

A temperature sensor 13 is embedded in the support wall 12. A sensor unit 14 is arranged next to the laminated body 20, and a signal line of the temperature sensor 13 is connected to the sensor unit 14. The signal line of the temperature sensor 13 is connected to the control board 30 (described later) via the sensor unit 14. A control circuit for determining the flow rate of the refrigerant is mounted on the control board 30. The measured value of the temperature sensor 13 is used as an estimated value of the temperature of the refrigerant flowing through the cooler 4a in contact with the support wall 12. The control circuit determines the amount of refrigerant supplied based on the measured value of the temperature sensor 13. The control circuit increases the supply amount of the refrigerant when the measured value of the temperature sensor 13 is high, and decreases the supply amount of the refrigerant when the measured value of the temperature sensor 13 is low.

FIG. 2 shows a plan view of the case 10 excluding the laminated body 20 from FIG. The case 10 is provided with a partition plate 11 that divides the internal space into upper and lower halves, and a through hole 11a is provided at a position corresponding to the laminated body 20 of the partition plate 11. The lower surface of the semiconductor module 3 faces the through hole 11a. Further, the support wall 12 that supports the laminated body 20 is located at the edge of the through hole 11a. A support column 19 that supports the laminated body 20 is also provided on the partition plate 11.

FIG. 3 shows a cross-sectional view taken along the line III-III of FIG. As described above, the semiconductor element 7 is embedded in the semiconductor module 3. The control terminal 31 of the semiconductor element 7 extends downward from the lower surface of the semiconductor module 3. The control terminal 31 extends downward from the partition plate 11 through the through hole 11a. The control board 30 described above is arranged below the partition plate 11, and the control terminal 31 of the semiconductor module 3 is connected to the control board 30. The control circuit mounted on the control board 30 not only adjusts the flow rate of the refrigerant, but also generates a drive signal for the semiconductor element 7 based on a command value given by the host control device. The control circuit sends the generated drive signal to each semiconductor element 7 through the control terminal 31.

The left end of the control board 30 is also supported by the partition plate 11, but in FIG. 3, the left end of the control board 30 is not shown. Further, in FIG. 3, reference numerals 7 and 31 are attached only to the semiconductor element and the control terminal of the rightmost semiconductor module 3, and the reference numerals to the semiconductor element and the control terminal of the other semiconductor module 3 are omitted.

As described above, the support wall 12 that supports one end of the laminated body 20 is arranged at the edge of the partition plate 11 of the case 10. In other words, the partition plate 11 connects the support wall 12 and the side wall 18. As shown in FIG. 3, the thickness t1 of the partition plate 11 is thinner than the thickness t2 of the support wall 12. Further, the thickness t1 of the partition plate 11 is thinner than the thickness t3 of the side wall 18 of the case 10.

As described above, the measured value of the temperature sensor 13 is used as an estimated value of the temperature of the refrigerant flowing through the cooler 4a in contact with the support wall 12. The support wall 12 is connected to the side wall 18 of the case 10 by a partition plate 11. When the thickness t2 of the partition plate 11 is large, heat is easily transferred between the support wall 12 and the side wall 18 (that is, the entire case 10) through the partition plate 11. In that case, the temperature of the support wall 12 moves away from the temperature of the refrigerant flowing through the cooler 4a. That is, the measured value of the temperature sensor 13 embedded in the support wall 12 has low accuracy as an estimated value of the refrigerant temperature. On the other hand, in the power converter 2 of the embodiment, the thickness t1 of the partition plate 11 is made thinner than the thickness t2 of the support wall 12, so that heat is transferred from the support wall 12 to the side wall 18 (that is, the entire case 10). Is suppressed. The temperature of the support wall 12 becomes close to the temperature of the cooler 4a in contact with the support wall 12. That is, the measured temperature of the temperature sensor 13 embedded in the support wall 12 becomes close to the refrigerant temperature. In the power converter 2 of the embodiment, the accuracy of the estimated value of the refrigerant temperature flowing through the cooler is higher than that of the conventional one. Therefore, the temperature of the semiconductor module 3 can be adjusted more appropriately.

The points to be noted regarding the techniques described in the examples will be described. The partition plate 11 is an example of a plate member that connects the side wall 18 of the case 10 and the support wall 12. In addition to the through hole 11a shown in FIG. 2, the partition plate 11 may be provided with a hole for lightening. The partition plate 11, the support wall 12, and the side wall 18 may be integrally formed or may be separate parts. For example, the partition plate 11, the support wall 12, and the side wall 18 may be integrally made by injection molding of aluminum.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2: Power converter 3: Semiconductor modules 4, 4a, 4b: Coolers 5a, 5b: Connecting pipe 6a: Refrigerant supply pipe 6b: Refrigerant discharge pipe 7: Semiconductor element 10: Case 11: Partition plate 11a: Through hole 12 : Support wall 13: Temperature sensor 14: Sensor unit 18: Side wall 19: Strut 20: Laminated body 29: Leaf spring 30: Control board

Claims (1)

A laminate in which a semiconductor module and a cooler are laminated, and
A case containing the laminated body and a case
A support wall that is in contact with the cooler at one end of the laminated body in the stacking direction in the case and supports the laminated body, and
The temperature sensor attached to the support wall and
A plate member that connects the side wall of the case and the support wall and is thinner than the thickness of the support wall.
Equipped with a power converter.

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