JP2021136697A - Power conversion device - Google Patents

Abstract

To provide a power conversion device capable of suppressing the effect of a magnetic field on a bus bar.SOLUTION: A disclosed power conversion device has multiple busbars 22. At least one busbar 22 has a hollow molding part 23 g forming hollow 23a. The busbar is placed outside the hollow 23a of the busbar 22 that has the hollow formation 23 g. Thus, the busbar 22 is prevented from being close to other bus bars 22, and is suppressed being affected by magnetic fields of other busbars 22.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to a power converter.

The power conversion device of Patent Document 1 has two bus bars having a hollow, and one bus bar is arranged in the hollow of the other bus bar.

Japanese Unexamined Patent Publication No. 2016-158426

Since the power converter arranges one bus bar in the hollow of the other bus bar, the entire outer surface of one bus bar faces the inner surface of the other bus bar. Further, in the power conversion device, one bus bar and the other bus bar may be arranged close to each other in order to reduce the size of the entire device. In that case, one bus bar may be strongly affected by the magnetic field due to the current flowing through the other bus bar.

The present disclosure has been made based on this circumstance, and an object of the present disclosure is to provide a power conversion device capable of suppressing the influence of a magnetic field on a bus bar.

The first aspect of the present disclosure for achieving the object is a power conversion unit that converts the power supplied from the battery and supplies it to the load, a power conversion unit, or a plurality of bus bars connected to the load. A power conversion device comprising, at least one of a plurality of bus bars having a hollow forming portion forming a hollow, and the bus bar being arranged outside the hollow of at least one bus bar having the hollow forming portion.

The power converter arranges the bus bar outside the hollow of at least one bus bar having a hollow forming portion. Therefore, it is possible to prevent the bass bars from being close to each other on the entire surface of the bus bars. Therefore, the power conversion device can suppress the currents from approaching each other as compared with a configuration having a bus bar in which another bus bar is arranged inside the hollow. As a result, the power converter can suppress the bus bar from being affected by the magnetic field due to the current flowing through the other bus bars.

It is a circuit diagram of the power conversion system of 1st Embodiment. It is a figure which showed the structure of the power conversion apparatus of 1st Embodiment. It is a figure which showed the structure of the power conversion apparatus of 1st Embodiment. It is sectional drawing of the IV-IV cross section of FIG. It is sectional drawing of the 3 phase bus bar of 1st Embodiment. It is a figure which showed the structure of the 3 phase bus bar of 1st Embodiment. It is sectional drawing of the VII-VII cross section of FIG. It is a figure which showed the structure of the bus bar of the 3rd comparative example. It is a figure which showed the structure of the bus bar of 1st Embodiment. It is a figure which showed the structure of the U-phase bus bar of 2nd Embodiment. It is sectional drawing of the cross section of XI-XI of FIG. It is sectional drawing of the three-phase bus bar of another embodiment. It is a figure which showed the structure of the three-phase bus bar of another embodiment.

Hereinafter, a plurality of embodiments of the present disclosure will be described with reference to the drawings. By assigning the same reference numerals to the corresponding components in each embodiment, duplicate description may be omitted. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other parts of the configuration. Further, not only the combination of the configurations specified in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if the combination is not specified. Further, an unspecified combination of the configurations described in the plurality of embodiments and modifications is also disclosed by the following description.

(First Embodiment)
As shown in FIG. 1, the power conversion system 1 includes a battery 11, a power conversion device 12, and a motor 13. The battery 11 supplies a direct current to the power conversion device 12 via the energized bus bar 20. The three-phase bus bar 22 is a name that collectively refers to the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25. The power conversion device 12 converts, for example, a direct current into a three-phase alternating current, and supplies the three-phase alternating current to the motor 13 via the three-phase bus bar 22. The motor 13 is, for example, a three-phase AC motor having three phases of U phase, V phase, and W phase.

As shown in FIG. 2, the power conversion device 12 includes an energizing bus bar 20, a power conversion unit 21, a three-phase bus bar 22, a current sensor 26, a control board 27, a smoothing capacitor 28, and a housing 29. The housing 29 internally houses the configuration of the power conversion device 12.

The power conversion unit 21 has a plurality of switching elements 21a. FIG. 2 illustrates only one set of the plurality of switching elements 21a. FIG. 2 omits the illustration of another set of switching elements 21a. The U-phase bus bar 23 is connected to the U-phase of the motor 13. Similarly, the V-phase bus bar 24 is connected to the V-phase of the motor, and the W-phase bus bar 25 is connected to the W-phase of the motor. In FIG. 2, the V-phase bus bar 24 and the W-phase bus bar 25 are not shown because they overlap the U-phase bus bar 23.

The U-phase bus bar 23 may be configured by one bus bar and may be connected to the output terminal 21c and the motor 13. Alternatively, the U-phase bus bar 23 may be configured by two bus bars, one bus bar is connected to the output terminal 21c and the other bus bar is connected to the motor 13. In that configuration, the two buses are connected so that the output terminal 21c and the motor 13 are electrically connected.

FIG. 2 shows a view of the power conversion device 12 when viewed in a YZ plane. The switching element 21a has a P terminal 21P connected to the positive electrode bus bar 20P, an N terminal 21N connected to the negative electrode bus bar 20N, and an output terminal 21c connected to the three-phase bus bar 22. Further, the switching element 21a has a signal terminal 21b connected to the control board 27.

The control board 27 controls on or off of the switching element 21a via the signal terminal 21b. Therefore, the power conversion device 12 controls the on or off of the plurality of switching elements 21a to supply the three-phase alternating currents having different cycles to the motor 13 via the three-phase bus bar 22.

In the present disclosure, the Y direction is the longitudinal direction in which the U-phase bus bar 23 extends. Further, the Y direction is the direction in which the switching element 21a and the smoothing capacitor 28 are arranged side by side. The Z direction is the longitudinal direction in which the signal terminal 21b extends. The Z direction is the longitudinal direction in which the N terminal 21N, the P terminal 21P, and the output terminal 21c extend.

In the smoothing capacitor 28, the positive electrode bus bar 20P, which is an energizing bus bar 20, is connected to the positive electrode, and the negative electrode bus bar 20N, which is the energizing bus bar 20, is connected to the negative electrode. As shown in FIG. 1, the positive electrode bus bar 20P is connected to the positive electrode of the battery 11. Similarly, the negative electrode bus bar 20N is connected to the negative electrode of the battery 11.

FIG. 3 shows a view of the power conversion device 12 when viewed in the XY plane. As shown in FIG. 3, for example, the plurality of switching elements 21a are stacked in the X direction with the cooling passage 30 interposed therebetween. The cooling passage 30 comes into contact with the switching element 21a, for example, on the YZ plane. Alternatively, the cooling passage 30 is arranged so that the YZ plane is close to the switching element 21a in the X direction without interposing a member.

FIG. 3 shows that the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25 are largely separated in the X direction, but since they are views for showing the positional relationship of each configuration, they have actual dimensions. Is different.

The cooling passage 30 is connected to the inflow pipe 31 and the outflow pipe 32. Since the switching element 21a is in contact with or in close proximity to the cooling passage 30, the refrigerant entered from the inflow pipe 31 is cooled when passing through the cooling passage 30. Then, the refrigerant that has passed through the cooling passage 30 is discharged to the outside of the power conversion device 12 via the outflow pipe 32. The refrigerant is, for example, LLC, and LLC flows from the water pump into the inflow pipe 31.

In the present disclosure, the plurality of bus bars are, for example, a U-phase bus bar 23, a V-phase bus bar 24, and a W-phase bus bar 25. As shown in FIG. 4, the U-phase bus bar 23 has, for example, an annular hollow forming portion 23 g. The hollow forming portion 23g forms a hollow 23a inside an annular shape. That is, the hollow 23a is surrounded by the hollow forming portion 23g.

Further, the hollow forming portion 23g is a conductive portion in which a current flows in the Y direction in the U-phase bus bar. Like the U-phase bus bar 23, the V-phase bus bar 24 and the W-phase bus bar 25 form a hollow by the hollow forming portion 23g. Although FIG. 4 shows an example in which the hollow forming portion 23g is annular, it may have a shape capable of forming a hollow inside, for example, a quadrangle or the like.

FIG. 5 is a cross-sectional view of the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25. For example, the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25 are arranged side by side in the X direction. As shown in FIG. 5, the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25 are arranged so that the surfaces forming the short side 23c face each other in the X direction.

Further, the U-phase bus bar 23 and the V-phase bus bar 24 and the V-phase bus bar 24 and the W-phase bus bar 25 are arranged in a state of being close to each other in the X direction. In the present disclosure, for example, as shown in FIG. 5, the distance D between the surfaces forming the short side 23c of the U-phase bus bar 23 and the V-phase bus bar 24 facing in the X direction is the width W of the long side 23b. Indicates a smaller state.

As shown in FIG. 5, the U-phase bus bar 23 is arranged outside the hollow 23a of the V-phase bus bar 24 and the W-phase bus bar 25. Similarly, the V-phase bus bar 24 and the W-phase bus bar 25 are arranged outside the hollow 23a of the other bus bars.

FIG. 6 shows a configuration in which the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25 are viewed in the XY plane. As shown in FIG. 6, for example, the U-phase bus bar 23 has a hollow forming portion 23g that forms the hollow 23a in at least a part of the range facing the V-phase bus bar 24 in the X direction.

In FIG. 6, it is described that the U-phase bus bar 23 forms the hollow 23a in a part of the range facing the V-phase bus bar 24 by the hollow forming portion 23g, but the hollow 23a is one end of the U-phase bus bar 23 in the Y direction. It may be formed on the entire U-phase bus bar 23 so as to penetrate the other end from the U-phase bus bar 23. That is, the U-phase bus bar 23 may have a tubular shape with both ends open in the X direction.

In FIG. 2, the U-phase bus bar 23 extends in one direction, that is, in the Y direction, and a current flows in the Y direction. The U-phase bus bar 23 is perpendicular to the Y direction, which is the energization direction, that is, the XZ cross section has a flat shape as shown in FIG. As shown in FIG. 4, the U-phase bus bar 23 has, for example, a portion where the hollow forming portion 23g forms a long side 23b and a portion forming a short side 23c. Similarly, the cross section of the V-phase bus bar 24 and the W-phase bus bar 25 in the direction perpendicular to the energization direction is a flat shape having a long side 23b and a short side 23c.

Further, as shown in FIG. 4, the U-phase bus bar 23 has a connecting portion 23d that connects the long side 23b and the short side 23c. The connecting portion 23d has an arc shape. Further, as shown in FIG. 4, the U-phase bus bar 23 may have a short side 23c and a connecting portion 23d in a series of arcs. Similarly, the V-phase bus bar 24 and the W-phase bus bar 25 have a connecting portion 23d that connects the long side 23b and the short side 23c.

The U-phase bus bar 23 is composed of a single plate. As shown in FIG. 4, the U-phase bus bar 23 has a welded portion 23e in which one plate is bent and one end and the other end are welded by welding. The U-phase bus bar 23 in FIG. 4 has a shape that is folded back at, for example, the connecting portion 23d. As shown in FIG. 4, the U-phase bus bar 23 welds, for example, the output terminal 21c of the switching element 21a to the welding portion 23e, and electrically connects the output terminal 21c to the switching element 21a. Similarly, the V-phase bus bar 24 and the W-phase bus bar 25 have a welded portion 23e in which one end and the other end are welded, and are welded to the output terminal 21c.

As shown in FIG. 5, the U-phase bus bar 23 has a welded portion 23e at a portion forming the long side 23b of the hollow forming portion 23g. Similarly, the V-phase bus bar 24 and the W-phase bus bar 25 have a welded portion 23e at a portion forming the long side 23b.

As shown in FIG. 7, in the power conversion device 12, an annular current sensor 26 is arranged so as to surround the outer circumference of the hollow forming portion 23g. In the present disclosure, the outer circumference indicates the circumference of the outer circumference. The inner surface of the current sensor 26 faces the outer surface of the hollow forming portion 23g and is arranged at a certain distance. That is, the current sensor 26 is arranged in a state of being close to the hollow forming portion 23g.

The current sensor 26 has a Hall element 26a connected to the control board 27 as shown in FIG. Further, as shown in FIG. 7, the Hall element 26a forms a part of the ring of the current sensor 26. In the current sensor 26, when the value of the current flowing through the U-phase bus bar 23 changes, the value of the magnetic field detected by the Hall element 26a changes. As a result, the current sensor 26 can detect the current value of the U-phase bus bar 23.

As shown in FIG. 5, the U-phase bus bar 23 and the V-phase bus bar 24 are arranged outside the hollow 23a of the other bus bar. The U-phase bus bar and the V-phase bus bar of the first comparative example are tubular bus bars that form a hollow inside by a hollow forming portion. In the power conversion device of the first comparative example, the U-phase bus bar is arranged in the hollow of the V-phase bus bar so that the central axes of the cylinders are aligned with each other.

Therefore, the entire outer surface of the U-phase bus bar of the first comparative example faces the inner surface of the V-phase bus bar. For example, in order to reduce the size of the entire power converter, the U-phase bus bar may be arranged in a state where the V-phase bus bar is brought close to each other.

In that case, the U-phase bus bar of the first comparative example comes close to the V-phase bus bar on the entire outer surface. Then, the current flowing through the U-phase bus bar approaches the current flowing through the V-phase bus bar. Therefore, the current flowing through the U-phase bus bar is affected by the proximity effect of the magnetic field of the current flowing through the V-phase bus bar, so that the inductance increases.

The surge voltage Vs flowing during switching is represented by Vs = L · dI / dt. Therefore, when the inductance L increases as in the first comparative example, the surge voltage Vs increases. Then, the power conversion device of the first comparative example generates a large surge, and there is a possibility that noise due to the surge causes a malfunction of the control circuit or the like.

On the other hand, the U-phase bus bar 23 of the present embodiment is arranged outside the hollow 23a of the V-phase bus bar 24 as shown in FIG. The U-phase bus bar 23 does not face the V-phase bus bar 24 on the entire surface. Therefore, the U-phase bus bar 23 can prevent the U-phase bus bar 23 from approaching the other bus bars on the entire surface.

Therefore, the U-phase bus bar 23 can suppress an increase in inductance due to the influence of the proximity effect of the magnetic field of the current flowing through the other bus bars. Further, since the U-phase bus bar 23 can prevent an increase in inductance, it is possible to suppress the occurrence of a surge.

In the U-phase bus bar of the first comparative example, the current density flowing in the U-phase bus bar is biased due to the proximity effect with the current flowing in the other bus bars. As a result, the U-phase bus bar may increase the amount of heat generated in the portion where the current density increases. On the other hand, the U-phase bus bar 23 of the present embodiment can reduce the influence of the proximity effect of other bus bars as described above, and thus can suppress the occurrence of current density bias. Therefore, the U-phase bus bar 23 can suppress an increase in the amount of heat generated by the U-phase bus bar 23.

In the U-phase bus bar 23, the hollow 23a is formed by the hollow forming portion 23g. Therefore, the U-phase bus bar 23 can not only dissipate heat to the outside of the hollow forming portion 23g when heat is generated, but also dissipate heat to the hollow 23a inside the hollow forming portion 23g. Therefore, the U-phase bus bar 23 can release heat more efficiently than the bus bar that does not have the hollow 23a.

An alternating current flows through the U-phase bus bar 23. In the case of an alternating current having a high frequency, the U-phase bus bar 23 makes it difficult for current to flow in the center of the bus bar due to the skin effect, and the current density near the outer surface becomes high. By forming the hollow 23a in the central portion where the current does not easily flow, the U-phase bus bar can suppress the consumption of the material in the portion where the current does not easily flow. Further, the U-phase bus bar 23 can be made lighter than the bus bar that does not form the hollow by forming the hollow 23a.

As shown in FIG. 4, the U-phase bus bar 23 is in contact with the output terminal 21c on the surface forming the long side 23b. The U-phase bus bar of the second comparative example has a circular tube-shaped cross section and does not have a long side. Since the U-phase bus bar of the second comparative example does not have a long side, a flat surface having a large area is not formed on the outer surface. Therefore, the U-phase bus bar of the second comparative example cannot make contact with the terminal on a flat surface, so that the contact area with the terminal cannot be widened.

On the other hand, the U-phase bus bar 23 of the present embodiment can form a wide flat surface by the surface forming the long side 23b, so that it can come into contact with the output terminal 21c over a wide area. As a result, the U-phase bus bar 23 can efficiently release the heat generated by energization to the output terminal 21c. Further, since the output terminal 21c is arranged close to the cooling passage 30 as shown in FIG. 3, it is cooled by the refrigerant passing through the cooling passage 30. Therefore, the heat transferred from the U-phase bus bar 23 to the output terminal 21c is absorbed by, for example, the refrigerant passing through the cooling passage 30.

For example, when a high-voltage current is passed through the U-phase bus bar, it is necessary to increase the cross section of the conductive portion perpendicular to the energization direction in order to secure an area through which the current flows. In that case, since the U-phase bus bar of the second comparative example has a circular tube shape having no long side and short side, when the energization direction is the Y direction, the cross-sectional shape is in both the X direction and the Z direction. May need to be increased.

On the other hand, in the U-phase bus bar 23 of the present embodiment, it is possible to secure an area for passing a high voltage current only by enlarging the portion of the hollow forming portion 23g that forms the long side 23b. That is, the U-phase bus bar 23 can secure an area for passing a high voltage only by increasing the portion forming the long side b of the hollow forming portion 23g in the X direction. Therefore, the U-phase bus bar 23 can suppress the increase of the portion forming the short side 23c of the hollow forming portion 23g in the Z direction in order to pass a high voltage current.

FIG. 8 is a cross-sectional view of the U-phase bus bar 123 and the V-phase bus bar 124 of the third comparative example. The U-phase bus bar 123 of the third comparative example has a shape in which the connecting portion 123d connecting the long side 123b and the short side 123c has an angle. In the U-phase bus bar 123 of the third comparative example, the connection portion 123d and the V-phase bus bar 124 are arranged so as to be separated by a distance d.

When the voltage between the two members is V and the distance between the two members is d, the voltage concentration E in the members is represented by E = η · V / d. η indicates the inequality ratio, and its value changes depending on the shape of the surface on which the members face each other.

The inequality ratio η is smaller as the shape of the surfaces facing each other is closer to a flat surface, that is, the larger the facing area is, and the larger the facing area is smaller like a needle. Since the connecting portion 123d of the third comparative example has a shape having a corner and faces the V-phase bus bar 124 at the corner, the area facing the V-phase bus bar 124 becomes very small.

Therefore, the connection portion 123d of the third comparative example may have a large inequality rate η, and as a result, the voltage concentration E at the connection portion 123d may increase. Then, when the voltage concentration E becomes larger than the value of the withstand voltage Eth of the material, the U-phase bus bar 123 of the comparative example causes dielectric breakdown between the connection portion 123d and the V-phase bus bar 124. Therefore, the U-phase bus bar 123 of the comparative example may cause dielectric breakdown with other members.

On the other hand, as shown in FIG. 9, in the U-phase bus bar 23 of the present embodiment, the shape of the connecting portion 23d is an arc shape. As shown in FIG. 9, the U-phase bus bar 23 faces the V-phase bus bar 24 separated by a distance d, for example, on the arcuate surface of the connecting portion 23d. Therefore, the U-phase bus bar 23 can face the V-phase bus bar 24 on an arcuate surface having a larger area than the corner.

Therefore, the U-phase bus bar 23 can suppress an increase in the inequality rate η as compared with the U-phase bus bar 23 of the third comparative example. As a result, the U-phase bus bar 23 can suppress the occurrence of dielectric breakdown with other members such as the V-phase bus bar 24. In FIG. 9, the U-phase bus bar 23 and the V-phase bus bar 24 are arranged as shown in order to explain the effect, but the arrangement of the bus bars is not limited to the arrangement as shown in FIG. 9, for example, FIG. As shown in 5, the bus bars are arranged in order in the X direction.

As shown in FIG. 4, the U-phase bus bar 23 is connected to the output terminal 21c by the welding portion 23e. On the other hand, the U-phase bus bar of the fourth comparative example is fastened to the output terminal of the switching element 21a with a screw. Since the U-phase bus bar of the fourth comparative example is fastened to the output terminal of the switching element 21a with a screw, the inductance may increase due to the fastening member. On the other hand, since the U-phase bus bar 23 of the present embodiment is directly connected to the output terminal 21c of the switching element 21a by welding, it is possible to suppress an increase in inductance due to fastening.

Further, since the U-phase bus bar of the fourth comparative example is connected to the output terminal of the switching element via a screw, when heat is transferred from the U-phase bus bar of the fourth comparative example to the output terminal, There is a risk that the heat transfer efficiency will decrease due to the use of screws. Therefore, the U-phase bus bar of the fourth comparative example may suppress the transfer of heat generated by energization to the output terminal 21c.

On the other hand, since the U-phase bus bar 23 is directly connected to the output terminal 21c, heat can be efficiently transferred from the U-phase bus bar 23 to the output terminal 21c. For example, the U-phase bus bar 23 releases the heat generated by itself to the output terminal 21c, and the heat released to the output terminal 21c is cooled by the cooling passage 30.

The U-phase bus bar of the fifth comparative example has a flat shape having a long side and a short side in cross section, and has an arc-shaped short side. Further, the U-phase bus bar of the fifth comparative example has a welded portion at a portion forming a short side. The cross section of the V-phase bus bar of the fifth comparative example has a flat shape like the U-phase bus bar. The U-phase bus bar and the V-phase bus bar of the fifth comparative example are arranged so that the surfaces of the portions forming the short sides face each other.

In the U-phase bus bar of the fifth comparative example, since the arc-shaped surfaces face each other with the V-phase bus bar, the facing area is smaller than that in the case of facing each other in a plane. Further, in the U-phase bus bar of the fifth comparative example, the welded portion is formed in an arc-shaped portion. The welded portion may have irregularities on the surface, for example, and the convex portion has a smaller area facing other members than the flat surface.

Therefore, in the U-phase bus bar of the fifth comparative example, since the welded portion having irregularities is formed on the arcuate surface, the area facing the V-phase bus bar may be small. That is, the U-phase bus bar of the fifth comparative example has a large inequality rate η as compared with the surface of the portion forming the long side which is a plane. As a result, the U-phase bus bar of the comparative example may cause dielectric breakdown between the welded portion and the facing component.

On the other hand, in the U-phase bus bar 23 of the present embodiment, as shown in FIG. 5, the welded portion 23e is provided in the portion forming the long side 23b. Since the surface of the portion forming the long side 23b has a planar shape, even if the welding portion 23e is provided, the inequality rate η is higher than when the welding portion is provided on the arcuate surface as in the fifth comparative example. It can be suppressed from becoming large. Therefore, the U-phase bus bar 23 can prevent dielectric breakdown from occurring between the U-phase bus bar 23 and the other component even when the U-phase bus bar 23 faces the other component.

Further, as shown in FIG. 5, in the U-phase bus bar 23, the surfaces of the portion forming the short side 23c in the X direction face each other with the V-phase bus bar 24, and the surface of the portion forming the long side 23b faces the other bus bars. Not facing each other. Therefore, the U-phase bus bar 23 can prevent the welded portions 23e from facing each other by providing the welded portion 23e at the portion forming the long side 23b. As a result, the U-phase bus bar 23 can suppress the occurrence of dielectric breakdown with the V-phase bus bar 24.

As shown in FIG. 4, since the U-phase bus bar 23 is connected to the output terminal 21c, a current due to high-speed switching flows from the switching element 21a. Therefore, the U-phase bus bar 23 may generate a large amount of heat due to the current due to high-speed switching. However, since the U-phase bus bar 23 can release heat to the hollow 23a, it is possible to suppress heat transfer from the U-phase bus bar 23 to surrounding parts.

As shown in FIG. 7, the current sensor 26 has an annular shape that covers one circumference of the hollow forming portion 23g of the U-phase bus bar 23. The U-phase bus bar 23 has a hollow 23a surrounded by the hollow forming portion 23g. Therefore, the heat generated by the current flowing through the hollow forming portion 23g is transferred to the hollow 23a.

Therefore, the U-phase bus bar 23 can suppress the heat generated in the hollow forming portion 23g from being transferred to the current sensor 26. As a result, even when a large current is passed through the hollow forming portion 23g, the U-phase bus bar 23 can suppress exceeding the heat-resistant temperature of the current sensor 26 as compared with the bus bar having no hollow 23a. Therefore, the U-phase bus bar 23 can detect the current with the current sensor 26 even when a large current is passed through the U-phase bus bar 23 as compared with the bus bar that does not have the hollow 23a.

(Second Embodiment)
The power conversion system 1 in this embodiment has the same configuration as that in the first embodiment. Therefore, in this embodiment, the same reference numerals as those in the first embodiment are used. In this embodiment, the points different from those of the first embodiment will be mainly described.

FIG. 10 shows a view of the U-phase bus bar 23 in the present embodiment when viewed in the XY plane. FIG. 11 shows a XI-XI cross section of the U-phase bus bar 23 of FIG. The U-phase bus bar 23 has a communication hole 23f that connects the hollow 23a and the outside of the hollow forming portion 23g at a portion forming the long side 23b of the hollow forming portion 23g. That is, the communication hole 23f is a hole that penetrates the outer surface 23i of the portion forming the long side 23b and the inner surface 23j on the hollow 23a side. As shown in FIG. 11, the U-phase bus bar 23 may have a plurality of communication holes 23f in the portion forming the long side 23b.

In the U-phase bus bar 23, the portions forming the long sides 23b face each other in the Z direction. The U-phase bus bar 23 may have a communication hole 23f only in the portion forming the long side 23b among the portions forming the long side 23b. Alternatively, as shown in FIG. 11, the U-phase bus bar 23 may have a communication hole 23f at both portions forming the long side 23b.

The U-phase bus bar 23 can allow the refrigerant and the like to pass through the inside of the hollow 23a and the outside of the hollow forming portion 23g by the communication hole 23f. As a result, in the U-phase bus bar 23, the hollow 23a is cooled by the refrigerant flowing in from the communication hole 23f, so that the U-phase bus bar 23 is cooled. Further, in the U-phase bus bar, even when the refrigerant does not flow, the heat released into the hollow 23a by natural convection is released to the outside of the hollow forming portion 23g through the communication hole 23f.

As shown in FIG. 11, when the U-phase bus bar 23 has the communication hole 23f, the U-phase bus bar 23 has a corner portion 23h at the opening edge of the communication hole 23f. For example, in the U-phase bus bar of the sixth comparative example, a communication hole is provided in a portion forming a short side, and the inequality rate η increases depending on the combination of the curved surface of the short side and the corner portion 23h. Therefore, the U-phase bus bar of the sixth comparative example has a high possibility of causing dielectric breakdown. On the other hand, since the U-phase bus bar 23 is provided with the communication hole 23f in the portion forming the long side 23b which is a flat surface, it is possible to suppress the occurrence of dielectric breakdown.

(Other embodiments)
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and the following embodiments are also included in the technical scope of the present disclosure. Various changes can be made within the range that does not deviate.

Although it is said that the power conversion device 12 is provided with the hollow 23a in the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25, it is sufficient that the hollow 23a is provided in at least one bus bar. For example, as shown in FIG. 12, in the V-phase bus bar 24, the hollow 23a is formed by the hollow forming portion 23g. The U-phase bus bar 23 and the W-phase bus bar 25 are bus bars in which the hollow 23a is not formed. The U-phase bus bar 23 and the W-phase bus bar 25 are arranged outside the hollow 23a of the V-phase bus bar 24.

It is assumed that the power conversion device 12 is provided with the hollow 23a in the three-phase bus bar 22, but the positive electrode bus bar 20P and the negative electrode bus bar 20N, which are the energizing bus bars 20, at least one of the energizing bus bars has a hollow forming portion 23g forming the hollow 23a. It may have a configuration.

For example, when the positive electrode bus bar 20P has a hollow forming portion 23g, the negative electrode bus bar 20N is arranged outside the hollow 23a formed by the hollow forming portion 23g of the positive electrode bus bar 20P. Further, in the positive electrode bus bar 20P and the negative electrode bus bar 20N, both bus bars may have a hollow forming portion 23g.

Although the U-phase bus bar 23 is said to have a hollow 23a, the hollow 23a may be provided in the entire U-phase bus bar 23, or may be provided in at least a part of the hollow 23a. The U-phase bus bar 23 does not provide the hollow 23a in a portion that requires strength against stress, vibration, or the like from another member, such as a portion connected to another member such as a terminal or a housing. Then, the U-phase bus bar 23 may be provided with a hollow 23a in a portion where strength is not required and is not in contact with other members.

As shown in FIG. 13, the U-phase bus bar 23, the V-phase bus bar 24, and the W-phase bus bar 25 may have a configuration having a plurality of hollow 23a. In that case, the U-phase bus bar 23 has a configuration in which a plurality of hollow 23a are intermittently formed by the hollow forming portion 23g, for example, in the Y direction.

The load may be an element such as a battery 11 or a capacitor 28 in addition to the motor.

The U-phase bus bar 23 is said to have a flat shape having a long side 23b and a short side 23c in cross section, but may have a non-flat shape such as a circle or a square.

Although it has been described that the U-phase bus bar 23 is welded to the output terminal 21c by the welding portion 23e, the U-phase bus bar 23 may be connected to the output terminal 21c by a fastening member.

Although it has been described that the U-phase bus bar 23 is provided with the welding portion 23e and the communication hole 23f at the portion forming the long side 23b, it may be provided at the portion forming the short side 23c.

Although the U-phase bus bar 23 is described as having a communication hole 23f, it may be configured not to have a communication hole 23f.

Although the three-phase bus bar 22 is described as having a current sensor 26, the three-phase bus bar 22 may not have the current sensor 26 or may be provided with the current sensor 26 only in a part of the bus bars.

Although the connecting portion 23d is assumed to have an arc shape, it may have another shape as long as it has a curved surface shape.

1 ... Power conversion system, 11 ... Battery, 12 ... Power conversion device, 13 ... Motor, 20 ... Energizing bus bar, 21 ... Power conversion unit, 21a ... Switching element, 21b ... signal terminal, 21c ... output terminal, 22 ... 3-phase bus bar, 23 ... U-phase bus bar, 23a ... hollow, 23b ... long side, 23c ... short side, 23d ... Connection part, 23e ... Welding part, 23f ... Communication hole, 23g ... Hollow forming part, 23h ... Corner part, 23i ... Outer surface, 23j ... Inner surface, 24 ... V-phase bus bar, 25 ... W-phase bus bar, 26 ... current sensor, 27 ... control board, 28 ... smoothing capacitor, 29 ... housing, 30 ... cooling passage , 31 ... Inflow pipe, 32 ... Outflow pipe

Claims (9)

A power converter (21) that converts the power supplied from the battery (11) and supplies it to the load.
The power conversion unit or a plurality of bus bars (22) connected to the load are provided.
At least one of the plurality of bus bars has a hollow forming portion (23 g) forming a hollow (23a).
The bus bar is a power conversion device arranged outside the hollow of the at least one bus bar having the hollow forming portion. The power conversion device according to claim 1, wherein the at least one bus bar has a flat shape having a long side (23b) and a short side (23c) in a cross section perpendicular to the direction in which an electric current flows. The power conversion device according to claim 2, wherein the at least one bus bar has a connecting portion (23d) connecting the long side and the short side of the cross section, and the connecting portion has an arc shape. The power conversion device according to any one of claims 1 to 3, wherein the at least one bus bar has a welded portion (23e) in which one end and the other end are welded. The at least one bus bar has a flat shape having a long side (23b) and a short side (23c) in a cross-sectional shape perpendicular to the direction in which an electric current flows.
The power conversion device according to claim 4, wherein the welded portion is provided in a portion forming the long side. The method according to any one of claims 1 to 5, wherein the at least one bus bar has a communication hole (23f) that communicates the hollow with the outside of the hollow forming portion in the hollow forming portion. Power converter. The at least one bus bar has a flat shape having a long side (23b) and a short side (23c) in a cross-sectional shape perpendicular to the direction in which an electric current flows.
The power conversion device according to claim 6, wherein the communication hole is provided in a portion forming the long side. The load is a three-phase AC motor.
The power conversion device according to any one of claims 1 to 7, wherein the plurality of bus bars connect the power conversion unit and the three-phase AC motor. A current sensor (26) for detecting a current flowing through at least one bus bar is provided.
The power conversion device according to claim 8, wherein the sensor is arranged on the outer periphery of the bus bar.

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