JP2025018450A - Power Conversion Equipment - Google Patents

Abstract

To provide a power conversion device which is downsized and saves cost.SOLUTION: The power conversion device includes a magnetic component and a cooling unit, the magnetic component having a magnetic core, the magnetic core having a coil, a main leg part on which the coil is wound, at least one leg part on which the coil is not wound, and a beam part for connecting the main leg part and the leg part to each other across the coil, and the cooling unit having a heat release part to which the coil is thermally connected and a cooling surface to which the magnetic core is thermally connected. The magnetic core has a first core provided on the other side in a Z-direction and thermally connected to the cooling surface and a second core provided on one side in the Z-direction. The end part of a protruding part of the coil protruding from the magnetic core to both sides thereof in a Y-direction, on the other side in the Z-direction and each heat release surface are thermally connected. The width in the Y-direction of a first beam part as a beam part of the first core is smaller than the width in the Y-direction of a second beam part as a beam part of the second core. Each heat release surface has a heat release surface expansion unit in which the heat release surface is expanded to the first beam part more than the second beam part which is made wider in the Y-direction.SELECTED DRAWING: Figure 2

Description

This disclosure relates to a power conversion device.

Due to recent environmental regulations and technological advances surrounding automobiles, electrified vehicles such as electric vehicles and hybrid vehicles in various sizes have been developed and are becoming more and more popular. Electrified vehicles that use a motor as a drive source are equipped with multiple power conversion devices. Power conversion devices installed in electrified vehicles include DC-DC converters that step down the voltage of a high-voltage battery and convert it into voltage for an auxiliary battery.

A DC-DC converter generally comprises an inverter circuit that converts high-voltage DC voltage into high-voltage AC voltage, a transformer that converts high-voltage AC into low-voltage AC, a rectifier circuit that rectifies the low-voltage AC using multiple rectifier elements and converts it into a DC pulse voltage, a smoothing reactor and smoothing capacitor that smooth the DC pulse voltage, and a housing that houses these components and has water channels for cooling heat-generating components such as the transformer and rectifier elements. The transformer and smoothing reactor are magnetic components that have windings and a magnetic core that easily generate heat. From the perspective of efficiently cooling the windings and magnetic core, transformers and smoothing reactors often adopt a planar structure.

In such DC-DC converters, all heat-generating components are placed flat on the cooling surface of the housing. As a result, the tallest heat-generating component naturally determines the height of the DC-DC converter itself. In most cases, the tallest heat-generating component is a transformer or smoothing reactor, so the height of the DC-DC converter and the size of its housing are determined by the height of the transformer and smoothing reactor.

For this reason, configurations that suppress the height of transformers have been disclosed (see, for example, Patent Document 1). In the configuration disclosed in Patent Document 1, the shape of the magnetic core is flattened to suppress the height of the transformer, and the beam portion of the magnetic core is shaped to protrude significantly outward relative to the center leg of the magnetic core. In addition, the outermost winding of the transformer winding made of sheet metal is used as the low-voltage winding, and the low-voltage winding is exposed from the resin coating that covers the winding, thereby reducing the height gap between the low-voltage winding and the magnetic core, thereby suppressing the height of the transformer.

Patent No. 5933673

In the transformer structure of Patent Document 1, the magnetic core is flattened, so the height of the transformer can be reduced. However, most of the windings are sandwiched between the magnetic cores on both sides in the height direction, so the windings cannot be thermally connected directly to the case, and are thermally connected to the case via the transformer terminals. Specifically, a center tap terminal provided in the center of the windings is electrically connected to the case, and the outer transformer terminals connected to the rectifying elements are thermally connected to the case via a heat transfer sheet or the like. Therefore, the temperature of the windings is maximum at the point farthest from the transformer terminals, and the heat dissipation path of the windings is the length of half a turn of the sheet metal.

In planar-structure magnetic components, the winding temperature is determined by the heat dissipation path length and loss. Therefore, from the perspective of miniaturization and cost reduction, it is desirable to shorten the heat dissipation path length and make the winding thinner to keep the winding temperature within the allowable temperature range, even if the loss is increased. However, in the above-mentioned Patent Document 1, the winding winding section is covered with a flat magnetic core, so the heat dissipation path length cannot be shortened, and the winding must be made thicker. As a result, the window dimensions of the magnetic core are enlarged, which causes the size of both the winding and the magnetic core to increase, and there is a problem that the costs of both are also increased.

Therefore, the present disclosure aims to obtain a power conversion device that is compact and low-cost by shortening the heat dissipation path of the windings, the winding width, and the window width of the magnetic core while maintaining the low profile of the magnetic components.

The power conversion device of the present disclosure comprises a magnetic component having a magnetic core with one or more windings, a main leg around which the winding is wound and extends in the direction of the winding central axis of the winding, at least one leg around which the winding is not wound and spaced apart from the main leg, and a beam section that connects the main leg and the leg across the winding, and a heat dissipation section to which the winding is thermally connected directly or via a heat dissipation member, and a cooling surface to which the magnetic core is thermally connected, and a cooler that cools the winding and the magnetic core, the direction of the winding central axis being the Z direction, the direction in which the beam section extends from the main leg towards one leg perpendicular to the Z direction being the X direction, and a heat dissipation section that is thermally connected to the magnetic core and a cooling surface ... The direction is the Y direction, the magnetic core has a first core provided on the other side in the Z direction and thermally connected to the cooling surface, and a second core provided on one side in the Z direction, the heat dissipation surface of the heat dissipation part is arranged on the other side in the Z direction of each of the protruding parts of the winding protruding from the magnetic core on both sides in the Y direction, the other end of each protruding part in the Z direction is thermally connected to each heat dissipation surface, the width in the Y direction of the first beam part, which is the beam part of the first core, is smaller than the width in the Y direction of the second beam part, which is the beam part of the second core, and each heat dissipation surface has a heat dissipation surface extension part in which the heat dissipation surface is extended on the first beam part side relative to the second beam part, which has a larger width in the Y direction.

According to the power conversion device of the present disclosure, the heat dissipation surface of the heat dissipation part is arranged on the other side in the Z direction of each of the protruding parts of the winding protruding from the magnetic core on both sides in the Y direction, and the other end of each protruding part in the Z direction is thermally connected to each heat dissipation surface, and the width in the Y direction of the first beam part, which is the beam part of the first core, is smaller than the width in the Y direction of the second beam part, which is the beam part of the second core, and each heat dissipation surface has a heat dissipation surface extension part in which the heat dissipation surface is extended on the first beam part side with respect to the second beam part whose width in the Y direction is larger. Therefore, by shortening the width in the Y direction of the first beam part, the area of the winding covered by the first core is reduced, and the heat dissipation area of the winding is expanded, so that the heat dissipation path of the winding can be shortened. Since the heat dissipation path of the winding is shortened, the winding width can be shortened, and the window width of the magnetic core can be shortened. Since the window width of the magnetic core is shortened, the mounting area of the magnetic core is reduced, and the power conversion device can be made smaller and less expensive. In addition, in a magnetic core shape in which the Y-direction width of the first beam portion is smaller than the Y-direction width of the second beam portion, the flat shape of the magnetic core is maintained and the low height of the magnetic components is maintained, so the height of the magnetic components can be reduced. Because the height of the magnetic components is reduced, the power conversion device can be made smaller and less expensive.

1 is a diagram illustrating an example of a circuit configuration of a power conversion device according to a first embodiment. 1 is an exploded perspective view showing a transformer of a power conversion device according to a first embodiment. FIG. 2 is an exploded perspective view of a transformer winding portion of the power conversion device according to the first embodiment. FIG. FIG. 2 is a plan view of a transformer of the power conversion device according to the first embodiment. 3 is a cross-sectional view showing a transformer of a power conversion device taken along the line AA in FIG. 2. FIG. 11 is an exploded perspective view showing a transformer of a power conversion device according to a second embodiment. FIG. 11 is an exploded perspective view showing a transformer of a power conversion device according to a third embodiment. FIG. 11 is an exploded perspective view showing a transformer of a power conversion device according to a fourth embodiment. FIG. 13 is an exploded perspective view showing a transformer and a smoothing reactor of a power conversion device according to a fifth embodiment. FIG. 13 is an exploded perspective view showing a transformer of a power conversion device according to a sixth embodiment. FIG. 13 is an exploded perspective view showing a transformer of a power conversion device according to a seventh embodiment. FIG. 13 is a diagram illustrating an example of a circuit configuration of a power conversion device according to a seventh embodiment.

The power conversion device according to the embodiment of the present disclosure will be described below with reference to the drawings. Note that the same or equivalent members and parts in each drawing will be denoted with the same reference numerals.

Embodiment 1.
Fig. 1 is a diagram showing an example of a circuit configuration of a power converter 100 according to a first embodiment, Fig. 2 is an exploded perspective view showing a transformer 3 of the power converter 100, Fig. 3 is an exploded perspective view of a transformer winding section 101 of the transformer 3 of the power converter 100, Fig. 4 is a plan view of the transformer 3 of the power converter 100, showing only the first core 11a, the cooler 17, and the heat transfer sheets 12a and 12b, the outer shape of the second core 11b is shown by a dashed line, the heat dissipation surfaces 19a and 19b and the heat dissipation surface extensions 24a, 24b, 24c, and 24d are shown by dashed lines, and Fig. 5 is a cross-sectional view showing the transformer 3 of the power converter 100 that is not disassembled, cut at the A-A cross section position in Fig. 2. In this embodiment, the power converter 100 is a step-down DC-DC converter that converts the DC voltage of a DC power source into a secondary side DC voltage insulated by the transformer 3 and outputs the DC voltage to a load such as a battery. The power conversion device 100 is not limited to a step-down converter, but may be a step-up converter.

<Main circuit configuration of power conversion device 100>
An example of the main circuit configuration of a power conversion device 100 will be described with reference to Fig. 1. In Fig. 1, the left side is the input side, and the right side is the output side. The power conversion device 100 is connected to a DC power source (not shown) on the left side, and to a load (not shown) such as a low-voltage battery on the right side. The power conversion device 100 includes an input capacitor 1 that smoothes the input voltage of an inverter circuit 2, an inverter circuit 2 having semiconductor switching elements 2a, 2b, 2c, and 2d, which converts an input DC voltage into an AC voltage and supplies it to a primary winding 3a, an insulated transformer 3 having a primary winding 3a and secondary windings 3b and 3c, which converts and outputs the voltage of the AC power output from the inverter circuit 2, a rectifier circuit 4 having a plurality of rectifier elements 4a and 4b that rectifies the AC voltage output from the secondary windings 3b and 3c, and a smoothing reactor 5 having a smoothing capacitor 6 and a reactor winding that smoothes the rectified voltage waveform that is the output of the rectifier circuit 4. The secondary windings 3b and 3c have a center tap 3d, which is connected to a smoothing reactor 5. The transformer 3 and the smoothing reactor 5 are magnetic components.

The inverter circuit 2 has multiple semiconductor switching elements 2a, 2b, 2c, and 2d in a full bridge configuration. In this embodiment, the inverter circuit 2 has four semiconductor switching elements, but the number of semiconductor switching elements is not limited to this. The semiconductor switching elements are, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) with diodes built in between the source and drain. Note that the semiconductor switching elements are not limited to MOSFETs, and may be self-extinguishing semiconductor switching elements such as IGBTs (Insulated Gate Bipolar Transistors) with diodes connected in reverse parallel. The semiconductor switching elements are formed on a semiconductor substrate made of a semiconductor material such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN).

The rectifying elements 4a and 4b are, for example, diodes. The secondary terminals of the transformer 3 other than the center tap terminal provided at the center tap 3d are connected to the rectifying elements 4a and 4b, respectively. In this embodiment, the rectifying elements 4a and 4b are each shown as a single diode, but they may be configured with two or more diodes connected in parallel. In addition, a self-extinguishing semiconductor switching element such as a MOSFET may be used as the rectifying element in the rectifier circuit 4.

<Configuration of power conversion device 100>
The configuration of the power conversion device 100 will be described with reference to Figs. 2 to 4. The power conversion device 100 includes a magnetic component and a cooler 17. The magnetic component includes a single or multiple windings and a magnetic core 11. In this embodiment, as shown in Fig. 2, the magnetic component is a transformer 3, and the transformer 3 includes multiple windings, and a transformer winding section 101 is formed from the multiple windings. The windings of the transformer 3 are the primary winding 3a and the secondary windings 3b and 3c shown in Fig. 1. In Fig. 3, the primary winding 3a is composed of a first primary winding 13a and a second primary winding 13b formed in a plate shape. The secondary winding 3b is composed of a first secondary winding 14a, and the secondary winding 3c is composed of a second secondary winding 14b, both of which are formed in a plate shape. The number of sheets of the primary winding 3a and the secondary windings 3b and 3c is not limited to this, and the shapes of the primary winding 3a and the secondary windings 3b and 3c are not limited to a plate shape. In this embodiment, the number of turns of each of the first primary winding 13a and the second primary winding 13b is 3, and the number of turns of each of the first secondary winding 14a and the second secondary winding 14b is 1, but the number of turns of each winding is not limited to this.

As shown in FIG. 2, the magnetic core 11 has main legs 23a and 23b around which the winding is wound and which extend in the direction of the winding central axis, at least one leg that is not wound with the winding and is spaced apart from the main legs 23a and 23b, and a beam that connects the main legs 23a and 23b to the legs across the winding. In this embodiment, the magnetic core 11 has two legs. The first leg is made up of legs 21b and 21d, and the second leg is made up of legs 21a and 21c. The magnetic core 11 is made up of, for example, a manganese-based ferrite core.

The cooler 17 is a housing in which the transformer 3 is disposed, and has heat dissipation sections 18a and 18b to which the windings are thermally connected directly or via a heat dissipation member, and a cooling surface 17a to which the magnetic core 11 is thermally connected, and cools the windings and the magnetic core 11. In this embodiment, a heat transfer sheet 12a, which is a heat dissipation member, is provided on the heat dissipation section 18a, and a heat transfer sheet 12b, which is a heat dissipation member, is provided on the heat dissipation section 18b. For example, a silicone rubber sheet or a urethane rubber sheet is used for the heat transfer sheets 12a and 12b. The cooler 17 has, for example, a refrigerant flow path (not shown) through which a refrigerant flows. For example, water or ethylene glycol liquid is used as the refrigerant. The cooler 17 is made of a metal such as aluminum.

The direction of the winding central axis is the Z direction, the direction perpendicular to the Z direction in which the beam extends from the main legs 23a, 23b toward one of the legs 21b, 21d is the X direction, and the direction perpendicular to the X and Z directions is the Y direction. In the figure, the direction indicated by each arrow is one side, and the opposite direction to the direction indicated by each arrow is the other side. The first legs 21b, 21d are disposed on one side of the main legs 23a, 23b in the X direction, and the second legs 21a, 21c are disposed on the other side of the main legs 23a, 23b in the X direction.

The magnetic core 11 has a first core 11a provided on the other side in the Z direction and thermally connected to the cooling surface 17a, and a second core 11b provided on one side in the Z direction. The surface on the other side in the Z direction of the first core 11a is, for example, coated with thermally conductive grease and thermally connected to the cooling surface 17a. The first core 11a, the transformer winding section 101, and the second core 11b are arranged in this order in the Z direction from the cooling surface 17a of the cooler 17. In this embodiment, since the magnetic core 11 has two legs, the first core 11a has a first beam section 22a that is a beam section connecting the main leg section 23a and the leg section 21a, and a first beam section 22b that is a beam section connecting the main leg section 23a and the leg section 21b. The second core 11b has a second beam portion 22c that is a beam portion connecting the main leg portion 23b and the leg portion 21c, and a second beam portion 22d that is a beam portion connecting the main leg portion 23b and the leg portion 21d.

The heat dissipation surface of the heat dissipation section is arranged on the other side in the Z direction of each of the protruding parts of the winding that protrude from the magnetic core 11 on both sides in the Y direction. The other end of each protruding part in the Z direction is thermally connected to each heat dissipation surface. Heat dissipation surface 19a is arranged on heat dissipation section 18a, and heat dissipation surface 19b is arranged on heat dissipation section 18b. Heat dissipation surfaces 19a and 19b are parts shown by dashed lines in Figures 2 and 4. The other end of the protruding part of the winding on one side in the Y direction in the Z direction is thermally connected to heat dissipation surface 19b, and the other end of the protruding part of the winding on the other side in the Y direction in the Z direction is thermally connected to heat dissipation surface 19a. As shown in Figure 4, heat dissipation surfaces 19a and 19b are parts that are provided directly below the first secondary winding 14a with a certain gap between them and the outer periphery of the second core 11b shown by the dashed line.

In this embodiment, the cooling surface 17a is arranged on the other side of the first core 11a in the Z direction, and the end of the first core 11a on the other side in the Z direction and the cooling surface 17a are thermally connected, and the heat dissipation parts 18a, 18b are parts of the cooler 17 protruding from the cooling surface 17a to one side in the Z direction. By configuring in this manner, the thermal resistance between the heat transfer sheets 12a, 12b and the cooler 17 is reduced, so that the temperature rise of the winding can be suppressed. Since the temperature rise of the winding is suppressed, the winding width can be shortened, and the window width (the dimension of the beam part in the X direction) of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, and the power conversion device 100 can be made smaller and less expensive.

The heat dissipation parts 18a, 18b are not limited to being parts of the cooler 17 protruding from the cooling surface 17a, and a separate heat dissipation member may be provided as the heat dissipation parts. However, by making the heat dissipation parts 18a, 18b parts of the cooler 17 protruding from the cooling surface 17a, the heat dissipation parts 18a, 18b can be easily manufactured. For example, when the cooler 17 is manufactured by aluminum die casting, the heat dissipation parts 18a, 18b can be manufactured at the same time as the cooler 17 is manufactured.

<Transformer Winding Section 101>
The configuration of the transformer winding section 101 will be described. As shown in FIG. 3, the windings of the transformer winding section 101 are arranged in the following order from the other side in the Z direction: the first secondary winding 14a, the first primary winding 13a, the second primary winding 13b, and the second secondary winding 14b. Each winding is formed in a plate shape curved on a plane. Each winding is formed, for example, by punching a sheet metal such as copper. The shape of the winding is not limited to a plate shape, but by forming the winding in a plate shape, unlike the case where the winding is a round wire or the like, it is possible to increase the mutually facing surfaces between each winding and between the first secondary winding 14a and the heat dissipation sections 18a and 18b. Since the mutually facing surfaces between each winding and between the first secondary winding 14a and the heat dissipation sections 18a and 18b are increased, the thermal resistance between them is reduced, and the cooling effect of the winding can be improved. Since the cooling effect of the winding is improved, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is reduced, the mounting area of the magnetic core 11 is reduced, so that the power conversion device 100 can be made smaller and less expensive.

The magnetic part is made of an insulating resin member and has a coating portion surrounding the winding, the other side of the coating portion in the Z direction is open, and the other side of the winding in the Z direction is exposed from the coating portion. In this embodiment, separators 15a, 15b, 15c, and 15d, which are coating portions, are provided in the transformer winding portion 101. Separator 15a is arranged between the first secondary winding 14a and the first primary winding 13a, separator 15b is arranged between the first primary winding 13a and the second primary winding 13b, separator 15c is arranged between the second primary winding 13b and the second secondary winding 14b, and separator 15d is arranged between the second secondary winding 14b and the heat sink 16. In this embodiment, the other side of the first secondary winding 14a in the Z direction is exposed from the coating portion. The other side of the first secondary winding 14a in the Z direction is thermally connected to the heat dissipation section 18a via the heat transfer sheet 12a on the other side in the Y direction, and is thermally connected to the heat dissipation section 18b via the heat transfer sheet 12b on one side in the Y direction.

By exposing the other side of the first secondary winding 14a in the Z direction from the coating, the thermal resistance between the first secondary winding 14a and the heat dissipation parts 18a, 18b is reduced, so that the cooling effect of the first secondary winding 14a can be improved. Since the cooling effect of the winding is improved, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so that the power conversion device can be made smaller and less expensive. In addition, in this embodiment, the first secondary winding 14a is a low-voltage side winding, and the insulation withstand voltage between the first secondary winding 14a and the heat dissipation parts 18a, 18b can be set low, so that heat transfer sheets 12a, 12b with high heat transfer coefficient and low insulation performance can be used between the first secondary winding 14a and the heat dissipation parts 18a, 18b. Furthermore, by providing a coating portion, insulation between each winding is ensured and the distance between each winding in the Z direction can be reduced, allowing the power conversion device 100 to be made smaller.

In this embodiment, multiple separators are provided as the coating portion, but this is not limited to this. The other side of the winding in the Z direction may be exposed from the coating portion, and the winding may be sealed with a resin member.

The inside of the separator 15b is open, and one end of the first primary winding 13a and one end of the second primary winding 13b are connected in series, for example by welding, at the open portion of the separator 15b. A primary winding terminal 25a is provided at the other end of the first primary winding 13a, and a primary winding terminal 25b is provided at the other end of the second primary winding 13b. The primary winding terminals 25a and 25b are connected to the output terminal of the inverter circuit 2 shown in FIG. 1.

As shown in FIG. 3, a secondary winding terminal 26c is provided at one end of the first secondary winding 14a, and a secondary winding terminal 26d is provided at one end of the second secondary winding 14b. The secondary winding terminal 26c and the secondary winding terminal 26d are connected, for example, by welding to form a center tap 3d. A secondary winding terminal 26b is provided at the other end of the first secondary winding 14a, and a secondary winding terminal 26a is provided at the other end of the second secondary winding 14b. The secondary winding terminal 26a is connected to the cathode of the rectifying element 4a shown in FIG. 1, and the secondary winding terminal 26b is connected to the cathode of the rectifying element 4b shown in FIG. 1. The center tap 3d is connected to the smoothing reactor 5 shown in FIG. 1.

The power conversion device 100 is made of a metal formed into a plate shape such as copper or aluminum, and includes a heat sink 16 arranged between the winding and the second beam portion. The heat sink 16 is thermally connected to the winding and thermally and electrically connected to the cooler 17. In this embodiment, the heat sink 16 is arranged between the second secondary winding 14b and the second beam portions 22c and 22d via the separator 15d. The heat sink 16 is thermally connected to the second secondary winding 14b. The heat sink 16 has connection ends 30a, 30b, and 30c as portions connected to the cooler 17. In this embodiment, the connection ends 30a and 30b are thermally and electrically connected to the heat sink 18b of the cooler 17 by screwing, and the connection end 30c is thermally and electrically connected to the heat sink 18a of the cooler 17 by screwing, using through holes provided in each of the connection ends 30a, 30b, and 30c. In this embodiment, the heat sink 16 has three connection ends, but the number of connection ends is not limited to this.

By configuring in this manner, the heat sink 16 thermally connected to the cooler 17 is disposed at one end of the transformer winding section 101 in the Z direction, so that it is possible to primarily cool the second primary winding 13b, which is located far from the cooler 17 and is likely to increase in temperature. Since the second primary winding 13b is primarily cooled, the winding width can be reduced, and therefore the window width of the magnetic core 11 can be reduced. Since the window width of the magnetic core 11 is reduced, the mounting area of the magnetic core 11 is reduced, and therefore the power conversion device 100 can be made smaller and less expensive.

<Y-direction width of beam and heat dissipation surface extension>
The width of the beam portion in the Y direction and the heat dissipation surface extension portion, which are the main parts of this disclosure, will be described. The width of the first beam portions 22a and 22b in the Y direction, which are the beam portions of the first core 11a, is smaller than the width of the second beam portions 22c and 22d in the Y direction, which are the beam portions of the second core 11b, and each heat dissipation surface has a heat dissipation surface extension portion in which the heat dissipation surface is extended to the first beam portions 22a and 22b side with respect to the second beam portions 22c and 22d, which have a larger width in the Y direction. In this embodiment, as shown in FIG. 4, the heat dissipation surface 19a has a heat dissipation surface extension portion 24a in which the heat dissipation surface is extended to the first beam portion 22a side, and a heat dissipation surface extension portion 24b in which the heat dissipation surface is extended to the first beam portion 22b side. The heat dissipation surface 19b has a heat dissipation surface extension portion 24c where the heat dissipation surface is extended on the first beam portion 22a side, and a heat dissipation surface extension portion 24d where the heat dissipation surface is extended on the first beam portion 22b side.

In addition, in this embodiment, when viewed in the Z direction, a portion of the second beam portion and the heat dissipation surface extension overlap. A portion on the other side of the second beam portion 22c in the Y direction overlaps with the heat dissipation surface extension 24a, and a portion on one side of the second beam portion 22c in the Y direction overlaps with the heat dissipation surface extension 24c. A portion on the other side of the second beam portion 22d in the Y direction overlaps with the heat dissipation surface extension 24b, and a portion on one side of the second beam portion 22d in the Y direction overlaps with the heat dissipation surface extension 24d.

By configuring in this way, the area covered by the first core 11a of the first secondary winding 14a is reduced by the amount of the shortened width of the first beam portions 22a and 22b in the Y direction, and the heat dissipation area of the first secondary winding 14a is expanded, so that the heat dissipation path of the first secondary winding 14a can be shortened. Since the heat dissipation path of the first secondary winding 14a is shortened, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so that the power conversion device 100 can be made smaller and less expensive. In addition, in the shape of the magnetic core 11 in which the width of the first beam portions 22a and 22b in the Y direction is made smaller than the width of the second beam portions 22c and 22d in the Y direction, the flat shape of the magnetic core 11 is maintained, and the low height of the transformer 3 is maintained, so that the height of the transformer 3 can be suppressed. Because the height of the transformer 3 is reduced, the power conversion device 100 can be made smaller and less expensive.

In this embodiment, the second beam portion and the heat dissipation surface extension portion overlap when viewed in the Z direction, but this is not limited to this. For example, if it is necessary to ensure a gap between the first core 11a and the heat dissipation surfaces 19a, 19b and the heat dissipation surface extension portions 24a to 24d that is equal to or greater than the width reduction of the first beam portions 22a, 22b due to dimensional tolerances of the cooler 17 and the magnetic core 11, the second beam portions 22c, 22d and the heat dissipation surface extension portions 24a to 24d are arranged in positions where they do not overlap. Even in this case, the heat dissipation surface extension portions 24a to 24d are provided and the heat dissipation surfaces 19a, 19b are expanded, so the heat dissipation path of the first secondary winding 14a can be shortened. Since the heat dissipation path of the first secondary winding 14a is shortened, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Because the window width of the magnetic core 11 is reduced, the mounting area of the magnetic core 11 is reduced, making it possible to reduce the size and cost of the power conversion device 100.

In this embodiment, the width in the Y direction of the first beam portions 22a, 22b of the first core 11a is smaller than the width in the Y direction of the main leg portion 23a and the legs 21a, 21b, and the heat dissipation surface extension portion is provided in a portion of the heat dissipation portion that protrudes from the side surface of the heat dissipation portion on the first beam portion side to the first beam portion side. The heat dissipation surface extension portion 24a is provided in a portion of the heat dissipation portion 18a that protrudes from the side surface of the first beam portion 22a side of the heat dissipation portion 18a to the first beam portion 22a side, and the heat dissipation surface extension portion 24b is provided in a portion of the heat dissipation portion 18a that protrudes from the side surface of the first beam portion 22b side of the heat dissipation portion 18a to the first beam portion 22b side. The heat dissipation surface extension 24c is provided on the portion of the heat dissipation section 18b that protrudes from the side surface of the heat dissipation section 18b on the first beam section 22a side toward the first beam section 22a side, and the heat dissipation surface extension 24d is provided on the portion of the heat dissipation section 18b that protrudes from the side surface of the heat dissipation section 18b on the first beam section 22b side toward the first beam section 22b side.

By configuring in this manner, the heat dissipation surface extensions 24a, 24b, 24c, and 24d can be provided without changing the size of the power conversion device 100 in the Y direction, so that the heat dissipation surface extensions 24a, 24b, 24c, and 24d can be easily formed in the power conversion device 100.

The effect of narrowing the width of the first beam portions 22a and 22b in the Y direction will be explained using FIG. 5. The arrows shown on the magnetic core 11 in FIG. 5 indicate heat dissipation paths. Heat dissipation paths 29a and 29b are heat dissipation paths for the second beam portion 22c, and heat dissipation paths 29c and 29d are heat dissipation paths for the second beam portion 22d. Heat dissipation path 29e is a heat dissipation path for the first beam portion 22a, and heat dissipation path 29f is a heat dissipation path for the first beam portion 22b.

In this embodiment, the width of the first beam portions 22a, 22b in the Y direction is shortened, and the cross-sectional area of the magnetic path formed in the X direction of the first beam portions 22a, 22b is reduced accordingly, so the magnetic flux density and loss density of the first beam portions 22a, 22b increase. The cross-sectional area of the magnetic path of a magnetic core for a transformer is determined by the constraints of either saturation magnetic flux density or thermal formation. With manganese ferrite material, which is a common core material, the loss density increases in proportion to 1.5 to the square of the frequency under the same magnetic flux density conditions, so in recent years, with the trend toward high-frequency operation of semiconductor switching elements, the cross-sectional area of the magnetic path tends to be restricted by thermal formation.

Therefore, the cross-sectional area of the magnetic path is restricted by the amount of increase in loss density. However, since the first beams 22a and 22b are arranged directly above the cooler 17, the cooling effect of the first beams 22a and 22b is large, so there is a margin for the allowable temperature of the magnetic core 11. On the other hand, the second beams 22c and 22d of the second core 11b are located farthest from the cooler 17, so the heat dissipation path is long and the temperature is the highest in the magnetic core 11. However, as shown in FIG. 5, the heat dissipation paths 29a, 29b, 29c, and 29d of the second beams 22c and 22d do not pass through the first beams 22a and 22b, so the heat dissipation paths 29a, 29b, 29c, and 29d are hardly affected by the increase in loss density in the first beams 22a and 22b, such as the increase in temperature. Therefore, in this embodiment, the width of the first beam portions 22a and 22b in the Y direction and the cross-sectional area of the magnetic path can be reduced without increasing the size of the magnetic core 11.

The above describes the case where the transformer 3 is a magnetic component, and the primary winding 3a and secondary windings 3b, 3c of the transformer 3 are windings of magnetic components. The magnetic component may be a smoothing reactor 5, and when the smoothing reactor 5 is a magnetic component, the reactor winding of the smoothing reactor 5 becomes a winding of a magnetic component. Whether the magnetic component is the transformer 3 or the smoothing reactor 5, with the configuration disclosed herein, the heat dissipation path of the winding is shortened, so the winding width can be shortened, and the window width of the magnetic core can be shortened. Since the window width of the magnetic core is shortened, the mounting area of the magnetic core is reduced, and the power conversion device 100 can be made smaller and less expensive.

In the step-down DC-DC converter shown in FIG. 1, a large current flows through the low-voltage side secondary windings 3b, 3c and reactor winding, so the copper loss in these windings is relatively large. For this reason, the secondary windings 3b, 3c and reactor winding of the step-down DC-DC converter must be thick, but by applying the configuration of the present disclosure, the dimensions of the mounting area for the windings are reduced, making it possible to reduce the cost of the power conversion device 100.

As described above, in the power conversion device 100 according to the first embodiment, the width in the Y direction of the first beam portions 22a and 22b, which are beam portions of the first core 11a, is smaller than the width in the Y direction of the second beam portions 22c and 22d, which are beam portions of the second core 11b, and each heat dissipation surface has a heat dissipation surface extension portion in which the heat dissipation surface is extended on the side of the first beam portions 22a and 22b relative to the second beam portions 22c and 22d, which have a larger width in the Y direction. Therefore, the area of the first secondary winding 14a covered by the first core 11a is reduced by the amount of the shortened width in the Y direction of the first beam portions 22a and 22b, and the heat dissipation area of the first secondary winding 14a is expanded, so that the heat dissipation path of the first secondary winding 14a can be shortened. Since the heat dissipation path of the first secondary winding 14a is shortened, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, and the power conversion device can be made smaller and less expensive. In addition, in a shape of the magnetic core 11 in which the Y-direction width of the first beam portions 22a, 22b is made smaller than the Y-direction width of the second beam portions 22c, 22d, the flat shape of the magnetic core 11 is maintained and the low height of the transformer 3 is maintained, so the height of the transformer 3 can be reduced. Since the height of the transformer 3 is reduced, the power conversion device 100 can be made smaller and less expensive.

When the winding is formed into a curved plate shape on a plane, unlike when the winding is a round wire, etc., the number of surfaces facing each other between the windings and between the first secondary winding 14a and the heat dissipation parts 18a, 18b can be increased. Since the number of surfaces facing each other between the windings and between the first secondary winding 14a and the heat dissipation parts 18a, 18b is increased, the thermal resistance between them is reduced, and the cooling effect of the windings can be improved. Since the cooling effect of the windings is improved, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, and the power conversion device 100 can be made smaller and less expensive.

When the magnetic component is made of an insulating resin member, has a coating portion surrounding the winding, has the other side of the coating portion in the Z direction open, and has the other side of the first secondary winding 14a in the Z direction exposed from the coating portion, the thermal resistance between the first secondary winding 14a and the heat dissipation portions 18a, 18b is reduced, so that the cooling effect of the first secondary winding 14a can be improved. Since the cooling effect of the winding is improved, the winding width can be shortened, so that the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so that the power conversion device 100 can be made smaller and less expensive.

When viewed in the Z direction, if the second beam portion and the heat dissipation surface extension portion overlap, the heat dissipation area of the first secondary winding 14a is further expanded, so the heat dissipation path of the first secondary winding 14a can be further shortened. Since the heat dissipation path of the first secondary winding 14a is further shortened, the winding width can be further shortened, so the window width of the magnetic core 11 can be further shortened. Since the window width of the magnetic core 11 is further shortened, the mounting area of the magnetic core 11 is further reduced, so the power conversion device 100 can be further miniaturized and reduced in cost.

When the cooling surface 17a is arranged on the other side of the first core 11a in the Z direction, the end of the first core 11a on the other side in the Z direction and the cooling surface 17a are thermally connected, and the heat dissipation parts 18a, 18b are parts of the cooler 17 protruding from the cooling surface 17a to one side in the Z direction, the thermal resistance between the heat transfer sheets 12a, 12b and the cooler 17 is reduced, so that the temperature rise of the winding can be suppressed. Since the temperature rise of the winding is suppressed, the winding width can be shortened, so that the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so that the power conversion device 100 can be made smaller and less expensive.

When the power conversion device 100 is made of metal and includes a heat sink 16 disposed between the winding and the second beam portion, and the heat sink 16 is thermally connected to the winding and thermally and electrically connected to the cooler 17, the heat sink 16 thermally connected to the cooler 17 is disposed at the end of the transformer winding portion 101 in the Z direction, so that the second primary winding 13b, which is located far from the cooler 17 and is likely to increase in temperature, can be cooled in a focused manner. Since the second primary winding 13b is cooled in a focused manner, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, and the power conversion device 100 can be made smaller and less expensive.

When the Y-direction width of the first beam portions 22a, 22b of the first core 11a is smaller than the Y-direction width of the main leg portion 23a and the legs 21a, 21b, and the heat dissipation surface extension portion is provided in the portion of the heat dissipation portion that protrudes from the side surface of the heat dissipation portion on the first beam portion side toward the first beam portion, the heat dissipation surface extension portions 24a, 24b, 24c, 24d can be provided without changing the Y-direction size of the power conversion device 100, so that the heat dissipation surface extension portions 24a, 24b, 24c, 24d can be easily formed in the power conversion device 100.

When the power conversion device 100 is a step-down converter or a step-up converter, the primary winding 3a and secondary windings 3b and 3c of the transformer 3 are windings of magnetic components, and the transformer 3 is a magnetic component, or the reactor winding of the smoothing reactor 5 is a winding of a magnetic component, and the smoothing reactor 5 is a magnetic component, whether the magnetic component is the transformer 3 or the smoothing reactor 5, with the configuration disclosed herein, the heat dissipation path of the winding is shortened, so the winding width can be shortened, and the window width of the magnetic core can be shortened. Since the window width of the magnetic core is shortened, the mounting area of the magnetic core is reduced, and the power conversion device 100 can be made smaller and less expensive.

Embodiment 2.
A power conversion device 100 according to embodiment 2 will be described. Fig. 6 is an exploded perspective view showing the transformer 3 of the power conversion device 100 according to embodiment 2. The transformer 3 of the power conversion device 100 according to embodiment 2 has a first core 11c and a second core 11d whose thickness is uniform in at least one direction, and is configured to improve the yield of the magnetic core 11.

The magnetic core 11 of this embodiment will be described. One of the first core and the second core is an E core with a uniform thickness in the Y direction, and the other of the first core and the second core is an I core with a uniform thickness in at least the Z direction. Alternatively, one of the first core and the second core is a U core with a uniform thickness in the Y direction, and the other of the first core and the second core is an I core with a uniform thickness in at least the Z direction. In the power conversion device 100 shown in FIG. 6, the second core 11d is an E core with a uniform thickness in the Y direction, and the first core 11c is an I core with a uniform thickness in the Z direction. The configuration of the magnetic core 11 is not limited to this, and the second core 11d may be a U core with a uniform thickness in the Y direction.

The reason for this configuration will be explained. The first core 11a shown in FIG. 2 of the first embodiment does not have a uniform thickness in any of the X, Y, and Z directions. If there are thin portions such as the first beam portions 22a and 22b, there is a risk that the yield will deteriorate during the manufacture of the magnetic core 11 and the cost of the magnetic core 11 will increase. In press molding, which is one of the manufacturing processes of the magnetic core 11, a press punch is applied from both sides of the magnetic core 11 that are in the same plane when viewed in either the Y direction or the Z direction in FIG. 2, and the magnetic core 11 is molded while applying pressure. However, in the case of the first core 11a, the only surface formed in the same plane is the other side in the Z direction. During press molding, the press punch is applied only to the other side in the Z direction and to the surfaces on one side of the Z direction of the legs 21a, 21b and the main leg portion 23a, and the surfaces on one side of the Z direction of the first beam portions 22a and 22b are pressed by a mold. Therefore, pressure is less likely to be applied to one side of the first beams 22a and 22b in the Z direction, and the density of the core material particles in the first beams 22a and 22b decreases. Because the density of the core material particles in the first beams 22a and 22b decreases, defects such as cracks are more likely to occur in the first beams 22a and 22b, and the yield of the first core 11a decreases, which causes an increase in the cost of the first core 11a.

In this embodiment, the first core 11c and the second core 11d have a uniform thickness in at least one direction, and the direction in which the thickness is uniform is the press direction when the magnetic core is molded. In FIG. 6, the second core 11d is the Y direction, and the first core 11c is the Z direction when molding, and the thickness of each core is uniform in the press direction. By configuring in this way, a core with a uniform thickness in at least one direction, such as the first core 11c and the second core 11d, can be pressed from both sides to all areas of the core during press molding, so that pressure can be applied evenly to the entire core. Since pressure is applied evenly to the entire core, the density of the core material particles is uniform throughout the core, and the deterioration of the manufacturing yield of the core can be suppressed. Since the deterioration of the manufacturing yield of the core is suppressed, the cost of the magnetic core 11 can be further reduced.

Embodiment 3.
A power conversion device 100 according to embodiment 3 will be described. Fig. 7 is an exploded perspective view showing the transformer 3 of the power conversion device 100 according to embodiment 3. The transformer 3 of the power conversion device 100 according to embodiment 3 has a configuration in which a potting material 27 is provided around the first core 11a.

The heat dissipation section 18c surrounds the outer periphery of the first core 11a and is provided with a gap from the outer periphery of the first core 11a. The gap between the outer periphery of the first core 11a and the heat dissipation section 18c is filled with potting material 27, which is a thermally conductive material, up to a height equal to or less than the height in the Z direction of the first beam sections 22a and 22b. The outer periphery of the first core 11a is the outer periphery of the first core 11a around the winding center axis of the winding. The heat dissipation section 18c is a part of the cooler 17 that protrudes from the cooling surface 17a to one side in the Z direction, and is formed in an annular shape.

By configuring in this manner, the outer periphery of the first beams 22a and 22b is thermally connected to the heat dissipation portion 18c via the potting material 27, so that the cooling effect of the first beams 22a and 22b, which have a small magnetic path cross-sectional area and high loss density, can be improved. Since the cooling effect of the first beams 22a and 22b is improved, the temperature of the first beams 22a and 22b can be lowered. In addition, since the cooling effect of the legs 21a and 21b and the main leg 23a of the first core 11a is also improved, there is a margin in the allowable temperature of the first core 11a and the second core 11b, so that the magnetic core 11 can be further reduced in size and cost. Since the magnetic core 11 is reduced in size and cost, the power conversion device 100 can be reduced in size and cost.

Embodiment 4.
A power conversion device 100 according to embodiment 4 will be described. Fig. 8 is an exploded perspective view showing the transformer 3 of the power conversion device 100 according to embodiment 4. The transformer 3 of the power conversion device 100 according to embodiment 4 is configured using a U-core for the magnetic core 11. The transformer winding section 101 has the same configuration as that in Fig. 3, and therefore description of the transformer winding section 101 will be omitted.

The magnetic core 11 of this embodiment will be described. One or both of the first core and the second core are U-cores. In the power conversion device 100 shown in FIG. 8, both the first core 11e and the second core 11f are U-cores. In this embodiment, the side of the heat dissipation section 18c facing the first beam section 22a, the leg section 21a, and the main leg section 23a in the first core 11e is formed on the same plane, so the heat dissipation surface extension section is formed in the heat dissipation surface extension section 24e, 24f shown by the dashed line. The heat dissipation section 18c is formed in a U-shape when viewed in the Z direction, and the bottom part of the U-shape has a part facing the main leg section 23a. The heat transfer sheet 12c is provided in a U-shape when viewed in the Z direction, and the bottom part of the U-shape of the heat dissipation section 18c is thermally connected to the first secondary winding 14a via the heat transfer sheet 12c.

By configuring in this way, when a UU core is used for the magnetic core 11, unlike the EE core or EI core shown in the previous embodiment, the other side of the transformer winding section 101 in the X direction is not covered by the magnetic core 11, so the heat dissipation area of the first secondary winding 14a on the other side of the transformer winding section 101 in the X direction can be enlarged. Since the heat dissipation area of the first secondary winding 14a is enlarged, the heat dissipation path of the first secondary winding 14a can be shortened. Since the heat dissipation path of the first secondary winding 14a is shortened, the winding width can be shortened, and the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so the power conversion device 100 can be made smaller and less expensive.

On the other hand, since there is only one first beam portion and one second beam portion, the cross-sectional area of the magnetic path required for the beam portion is twice that of the EE core and EI core. For this reason, compared to the case where the EE core and EI core are applied, the first core 11e has a wider width in the Y direction of the first beam portion 22a perpendicular to the magnetic path, the heat dissipation path of the winding is longer, and the second core 11f has a higher core height. Therefore, by applying the configuration disclosed herein, it is possible to obtain the effect of suppressing the height of the magnetic core 11.

Embodiment 5.
A power conversion device 100 according to embodiment 5 will be described. Fig. 9 is an exploded perspective view showing the transformer 3 and the smoothing reactor 5 of the power conversion device 100 according to embodiment 5. The transformer 3 and the smoothing reactor 5 of the power conversion device 100 according to embodiment 5 are configured such that the magnetic cores 11 of the transformer 3 and the smoothing reactor 5 are integrated together, and a common magnetic path is formed in the magnetic core 11.

In this embodiment, the magnetic components are a transformer 3 and a smoothing reactor 5. The magnetic core 11 has one leg 32a, 32b, and first main leg 34a, 34c and second main leg 34b, 34d, which are main leg portions. The first core 11g has a leg 32a, a first main leg 34a, and a second main leg 34b, and the leg 32a and the first main leg 34a are connected by a first beam portion 33a, and the leg 32a and the second main leg 34b are connected by a first beam portion 33b. The second core 11h has a leg 32b, a first main leg 34c, and a second main leg 34d, and the leg 32b and the first main leg 34c are connected by a second beam portion 33c, and the leg 32b and the second main leg 34d are connected by a second beam portion 33d.

The legs 32a, 32b, the first main legs 34a, 34c, and the second main legs 34b, 34d are arranged in the X direction or in the opposite direction to the X direction in the order of the first main legs 34a, 34c, the legs 32a, 32b, and the second main legs 34b, 34d. The primary winding and the secondary winding, which are windings and transformer windings, are wound around the first main legs 34a, 34c, and the reactor winding, which is a winding, is wound around the second main legs 34b, 34d. In FIG. 9, the primary winding and the secondary winding form a transformer winding section 101, and the reactor winding forms a reactor winding section 102. A common magnetic path for the primary winding, secondary winding, and reactor winding is formed in the legs 32a, 32b. The reactor winding section 102 is formed in a plate shape and has two windings connected at one end. Reactor terminals 28a and 28b are formed at the other ends of the two windings. Reactor terminal 28a is connected to secondary winding terminal 26c, which is a center tap, and reactor terminal 28b is connected to smoothing capacitor 6 shown in FIG. 1.

The magnetic flux of the transformer 3 flows through the first main legs 34a, 34c, the first beam 33a, the second beam 33c, and the legs 32a, 32b. The magnetic flux of the smoothing reactor 5 flows through the second main legs 34b, 34d, the first beam 33b, the second beam 33d, and the legs 32a, 32b. In this embodiment, the side of the heat dissipation section 18d facing the first beam 33a, 33b, the leg 32a, the first main leg 34a, and the second main leg 34b in the first core 11g is formed on the same plane, so that the heat dissipation surface extensions are formed in the heat dissipation surface extensions 24e, 24f, 24g, and 24h shown by the dashed lines. The heat dissipation surface extensions 24e and 24f are provided for the transformer winding section 101 and are thermally connected to the transformer winding section 101 via the heat transfer sheet 12c. The heat dissipation surface extension portion 24g is provided for the reactor winding portion 102 and is thermally connected to the reactor winding portion 102 via the heat transfer sheet 12d. The heat dissipation surface extension portion 24h is provided for the reactor winding portion 102 and is thermally connected to the reactor winding portion 102 via the heat transfer sheet 12e.

By configuring in this way, the cross-sectional area of the magnetic path required for the beam portion is twice that of the EE core and EI core, as in the configuration of the UU core shown in FIG. 8. Therefore, compared to the case where the EE core and EI core are applied, the first core 11g has a wider width in the Y direction of the first beam portions 33a and 33b perpendicular to the magnetic path, the heat dissipation path of the winding is longer, and the second core 11h has a higher core height. Therefore, by applying the configuration of the present disclosure, it is possible to obtain the effect of suppressing the height of the magnetic core 11. In addition, since a common magnetic path for the primary winding, secondary winding, and reactor winding is formed in the legs 32a and 32b, the magnetic core 11 can be made smaller. Since the magnetic core 11 is made smaller, the power conversion device 100 can be made smaller.

Embodiment 6.
A power conversion device 100 according to embodiment 6 will be described. Fig. 10 is an exploded perspective view showing the transformer 3 of the power conversion device 100 according to embodiment 6. The transformer 3 of the power conversion device 100 according to embodiment 6 has a configuration in which the widths of the main legs 23c, 23d in the X direction and the Y direction are different from those of embodiment 1.

The magnetic core 11 of this embodiment will be described. The Y-direction width of the first beam portions 22a, 22b of the first core 11i is the same as the Y-direction width of the main leg portion 23c. The Y-direction width of the main leg portion 23d of the second core 11j is the same as the Y-direction width of the main leg portion 23c of the first core 11i. The X-direction width of the main legs 23c, 23d is increased so that the magnetic path cross-sectional area of the main legs 23c, 23d is the same as that of the second beam portions 22c, 22d and legs 21c, 21d.

In the configuration of the heat dissipation sections 18a and 18b shown in the first embodiment, two protrusions are formed on each of the heat dissipation sections 18a and 18b so as to follow the shape of the first core 11a when viewed in the Z direction, and the heat dissipation surface extensions 24a to 24d are provided on each of the protrusions. By using the configuration of this embodiment shown in FIG. 10, the side surfaces of the first beam sections 22a and 22b and the main leg section 23c of the first core 11i are flush with each other, so that the protrusions of the heat dissipation sections 18a and 18b are consolidated into one location each. The heat dissipation surface extensions 24a and 24b are provided on one protrusion of the heat dissipation section 18a, and the heat dissipation surface extensions 24c and 24d are provided on one protrusion of the heat dissipation section 18b. Since the protrusions of the heat dissipation sections 18a and 18b are consolidated into one location each, the cooler 17 can be easily manufactured, and the productivity of the power conversion device 100 can be improved. This improves the productivity of the power conversion device 100, thereby reducing the manufacturing cost of the power conversion device 100.

Embodiment 7.
A power conversion device 100 according to embodiment 7 will be described. Fig. 11 is an exploded perspective view showing the transformer 3 of the power conversion device 100 according to embodiment 7, and Fig. 12 is a diagram showing an example of a circuit configuration of the power conversion device 100 according to embodiment 7. In the power conversion device 100 according to embodiment 7, the connection configuration between the transformer 3 and the rectifier circuit 4 is different from that of embodiment 1.

The power conversion device 100 of this embodiment is a step-down converter. Each of the multiple rectifying elements is connected between the other end of the secondary winding and the smoothing reactor, and one end of the secondary winding is electrically connected to the heat dissipation section. This configuration will be described with reference to Figures 11 and 12. In the power conversion device 100 of this embodiment, as shown in Figure 12, the center tap 3d of the transformer 3 is connected to ground (GND), and the rectifying elements 4a and 4b are connected between the secondary windings 3b and 3c of the transformer 3 and the smoothing reactor 5. As shown in Figure 11, the secondary winding terminal 26c at one end of the first secondary winding 14a and the secondary winding terminal 26d at one end of the second secondary winding 14b are connected, for example, by welding, to form a center tap terminal that is the center tap 3d. The potential of the cooler 17 is ground, and the center tap terminal is connected to the heat dissipation section 18a of the cooler 17. For example, a screw hole 35 is provided on one side of the heat dissipation section 18a in the Z direction, and the center tap terminal is screwed into the screw hole 35. The center tap terminal and the heat dissipation section 18a are electrically and thermally connected by the screw fastening.

A heat dissipation surface 19c is disposed adjacent to the screw hole 35 on the heat dissipation section 18a on the first core 11a side of the screw hole 35. The heat dissipation surface 19c is electrically and thermally connected to the other side of the first secondary winding 14a in the Z direction. A heat dissipation surface extension 24b is provided between the heat dissipation surface 19c and the first core 11a, and is electrically and thermally connected to the other side of the first secondary winding 14a in the Z direction.

By configuring in this manner, the cooler 17 and the first secondary winding 14a are at the same potential, so the cooler 17 and the first secondary winding 14a can be directly connected to the heat dissipation surface 19c and the heat dissipation surface extension portion 24b without using an insulating heat transfer sheet or the like. Since the cooler 17 and the first secondary winding 14a are directly connected, the thermal resistance between the winding and the cooler 17 can be reduced. Since the thermal resistance between the winding and the cooler 17 is reduced, the cooling effect of the winding can be improved. Since the cooling effect of the winding is improved, the winding width can be shortened, so the window width of the magnetic core 11 can be shortened. Since the window width of the magnetic core 11 is shortened, the mounting area of the magnetic core 11 is reduced, so the power conversion device 100 can be made smaller and less expensive.

Although the above describes the embodiment focusing on the transformer, the present disclosure may be applied to, for example, a planar reactor using a dust core material. When the present disclosure is applied and the height of the magnetic core is the same, the cross-sectional area of the magnetic path is reduced in proportion to the shortening of the width of the first beam part of the first core in the Y direction. When l is the magnetic path length, μ is the magnetic permeability, A is the cross-sectional area of the magnetic path, and N is the number of turns, the L value of the reactor is expressed by the formula (1).
L=μ・N ²・A/l...(1)
From formula (1), the L value of the first beam portion of the first core decreases in proportion to the cross-sectional area A of the magnetic path.

On the other hand, unless the gap between the first core and the heat dissipation section is dominant over the heat dissipation path length of the winding, the heat dissipation path length of the winding is shortened in proportion to the shortening of the width in the Y direction, and the temperature rise of the winding decreases in proportion to the shortening of the heat dissipation path length, so the winding width is also shortened in proportion to the shortening of the heat dissipation path length. As a result, unless the gap between the winding and each leg is dominant over the core window width, the core window width and the magnetic path length of the first beam part of the first core are shortened in proportion to the winding width, so according to formula (1), A/l is constant and the L value hardly changes. Furthermore, since the L value of the second beam part of the second core increases inversely proportional to the shortening of the magnetic path length, the L value of the entire reactor may increase. Therefore, the L value does not decrease by applying the present disclosure, and the reactor can be made smaller and less expensive.

In addition, for example, the configuration of the present disclosure may be applied to a gapped reactor using a manganese-based ferrite core material. In the case of a gapped reactor, the cross-sectional area of the core is restricted by the saturation magnetic flux density. Since the saturation magnetic flux density of a manganese-based ferrite core material has a negative temperature characteristic, there is no problem in reducing the cross-sectional area of the first core, which has a low temperature, until it reaches an arbitrary saturation magnetic flux density. In addition, when Rcore is the magnetic resistance in the ferrite core, Rg is the magnetic resistance in the gap, and N is the number of turns, the L value of the gapped reactor is expressed by the formula (2).
L= ^N2 /(Rcore+Rg)...(2)
When l is the magnetic path length, μ is the magnetic permeability, and A is the cross-sectional area of the magnetic path, the magnetic resistance R is expressed by equation (3).
R=l/μ・A...(3)
In addition, since the relative permeability of the manganese-based ferrite core material is 1000 or more compared to the relative permeability of air, which is 1, the relationship of Rcore<<Rg is satisfied. Therefore, even if the cross-sectional area of the magnetic path of the first beam portion of the first core is reduced by applying the present disclosure, the L value hardly changes.

Although the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations.
Therefore, countless modifications not exemplified are assumed within the scope of the technology disclosed in this specification, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment.

Various aspects of the present disclosure are summarized below as appendices.
(Appendix 1)
a magnetic component having a magnetic core provided with one or more windings, a main leg portion around which the winding is wound and which extends in a direction of a winding central axis of the winding, at least one leg portion around which the winding is not wound and which is disposed at a distance from the main leg portion, and a beam portion that connects the main leg portion and the leg portion across the winding;
a heat dissipation unit to which the winding is thermally connected directly or via a heat dissipation member, and a cooling surface to which the magnetic core is thermally connected, and a cooler that cools the winding and the magnetic core,
The direction of the winding central axis is defined as a Z direction, the direction perpendicular to the Z direction and extending from the main leg portion to one of the legs is defined as an X direction, and the direction perpendicular to the X direction and the Z direction is defined as a Y direction,
The magnetic core includes a first core provided on the other side in the Z direction and thermally connected to the cooling surface, and a second core provided on one side in the Z direction,
a heat dissipation surface of the heat dissipation unit is disposed on the other side in the Z direction of each of the protruding portions of the winding that protrude from the magnetic core on both sides in the Y direction,
an end portion of each of the protruding portions on the other side in the Z direction and each of the heat dissipation surfaces are thermally connected to each other;
a width in the Y direction of a first beam portion that is the beam portion of the first core is smaller than a width in the Y direction of a second beam portion that is the beam portion of the second core,
A power conversion device in which each of the heat dissipation surfaces has a heat dissipation surface extension portion in which the heat dissipation surface is extended on the side of the first beam portion relative to the second beam portion, whose width in the Y direction is increased.
(Appendix 2)
2. The power conversion device according to claim 1, wherein the winding is formed into a curved plate shape on a plane.
(Appendix 3)
the magnetic component is made of an insulating resin material and has a coating portion surrounding the winding,
3. The power conversion device according to claim 1, wherein the other side of the coating portion in the Z direction is open, and the other side of the winding in the Z direction is exposed from the coating portion.
(Appendix 4)
The power conversion device according to any one of claims 1 to 3, wherein a portion of the second beam portion and the heat dissipation surface extension portion overlap when viewed in the Z direction.
(Appendix 5)
The cooling surface is disposed on the other side of the first core in the Z direction,
an end portion of the first core on the other side in the Z direction and the cooling surface are thermally connected to each other;
The power conversion device according to any one of claims 1 to 4, wherein the heat dissipation portion is a part of the cooler protruding from the cooling surface to one side in the Z direction.
(Appendix 6)
a heat sink made of metal and disposed between the winding and the second beam portion;
6. The power conversion device according to any one of claims 1 to 5, wherein the heat sink is thermally connected to the winding and thermally and electrically connected to the cooler.
(Appendix 7)
A power conversion device described in any one of Appendices 1 to 6, wherein one of the first core and the second core is an E core having a uniform thickness in the Y direction, and the other of the first core and the second core is an I core having a uniform thickness at least in the Z direction, or one of the first core and the second core is a U core having a uniform thickness in the Y direction, and the other of the first core and the second core is an I core having a uniform thickness at least in the Z direction.
(Appendix 8)
the heat dissipation portion surrounds an outer circumferential portion of the first core and is provided with a gap between the heat dissipation portion and the outer circumferential portion of the first core,
A power conversion device as described in Appendix 5, wherein the gap between the outer periphery of the first core and the heat dissipation portion is filled with a thermal conductive material to a height equal to or less than the height of the first beam portion in the Z direction.
(Appendix 9)
The power conversion device according to any one of appendix 1 to 8, wherein one or both of the first core and the second core are U cores.
(Appendix 10)
the magnetic core has one of the legs and a first main leg portion and a second main leg portion that are the main leg portions,
the leg portion, the first main leg portion, and the second main leg portion are arranged in the X direction or in a direction opposite to the X direction in the order of the first main leg portion, the leg portion, and the second main leg portion;
The winding includes a primary winding and a secondary winding, which are transformer windings, wound around the first main leg portion,
The reactor winding is wound around the second main leg portion,
The power conversion device according to any one of claims 1 to 9, wherein a common magnetic path for the primary winding, the secondary winding, and the reactor winding is formed in the leg portion (Supplementary Note 11).
The power conversion device according to any one of claims 1 to 10, wherein a width in the Y direction of the first beam portion of the first core and a width in the Y direction of the main leg portion are the same.
(Appendix 12)
a width in the Y direction of the first beam portion of the first core is smaller than a width in the Y direction of the main leg portion and the leg portion,
A power conversion device described in any one of appendix 1 to 11, wherein the heat dissipation surface extension portion is provided in a portion of the heat dissipation portion that protrudes from a side surface of the heat dissipation portion on the side of the first beam portion toward the first beam portion.
(Appendix 13)
a transformer having a primary winding and a secondary winding;
an inverter circuit having a semiconductor switching element and supplying power to the primary winding;
a rectifier circuit having a plurality of rectifier elements for rectifying the AC voltage output from the secondary winding;
a smoothing reactor having a smoothing capacitor and a reactor winding for smoothing an output of the rectifier circuit;
13. The power conversion device according to any one of appendix 1 to 12, wherein the primary winding and the secondary winding of the transformer are the windings and the transformer is the magnetic component, or the reactor winding of the smoothing reactor is the winding and the smoothing reactor is the magnetic component.
(Appendix 14)
The step-down converter,
each of the plurality of rectifying elements is connected between the other end of the secondary winding and the smoothing reactor;
14. The power conversion device according to claim 13, wherein one end of the secondary winding is electrically connected to the heat dissipation portion.

1 Input capacitor, 2 Inverter circuit, 2a, 2b, 2c, 2d Semiconductor switching element, 3 Transformer, 3a Primary winding, 3b, 3c Secondary winding, 3d Center tap, 4 Rectifier circuit, 4a, 4b Rectifier element, 5 Smoothing reactor, 6 Smoothing capacitor, 11 Magnetic core, 11a, 11c, 11e, 11g, 11i First core, 11b, 11d, 11f, 11h, 11j Second core, 12a, 12b, 12c, 12d, 12e Heat transfer sheet, 13a First primary winding, 13b Second primary winding, 14a First secondary winding, 14b Second secondary winding, 15a, 15b, 15c, 15d Separator, 16 Heat sink, 17 Cooler, 17a Cooling surface, 18a, 18b, 18c, 18d Heat dissipation portion, 19a, 19b, 19c Heat dissipation surface, 21a, 21b, 21c, 21d Leg portion, 22a, 22b First beam portion, 22c, 22d Second beam portion, 23a, 23b, 23c, 23d Main leg portion, 24a, 24b, 24c, 24d, 24e, 24f, 24g, 24h Heat dissipation surface extension portion, 25a, 25b Primary winding terminal, 26a, 26b, 26c, 26d Secondary winding terminal, 27 Potting material, 28a, 28b Reactor terminal, 29a, 29b, 29c, 29d, 29e, 29f Heat dissipation path, 30a, 30b, 30c Connection end portion, 32a, 32b Legs, 33a, 33b First beams, 33c, 33d Second beams, 34a, 34c First main legs, 34b, 34d Second main legs, 35 Screw holes, 100 Power converter, 101 Transformer windings, 102 Reactor windings

Claims (14)

a magnetic component having a magnetic core provided with one or more windings, a main leg portion around which the winding is wound and which extends in a direction of a winding central axis of the winding, at least one leg portion around which the winding is not wound and which is disposed at a distance from the main leg portion, and a beam portion that connects the main leg portion and the leg portion across the winding;
a heat dissipation unit to which the winding is thermally connected directly or via a heat dissipation member, and a cooling surface to which the magnetic core is thermally connected, and a cooler that cools the winding and the magnetic core,
The direction of the winding central axis is defined as a Z direction, the direction perpendicular to the Z direction and extending from the main leg portion to one of the legs is defined as an X direction, and the direction perpendicular to the X direction and the Z direction is defined as a Y direction,
The magnetic core includes a first core provided on the other side in the Z direction and thermally connected to the cooling surface, and a second core provided on one side in the Z direction,
a heat dissipation surface of the heat dissipation unit is disposed on the other side in the Z direction of each of the protruding portions of the winding that protrude from the magnetic core on both sides in the Y direction,
an end portion of each of the protruding portions on the other side in the Z direction and each of the heat dissipation surfaces are thermally connected to each other;
a width in the Y direction of a first beam portion that is the beam portion of the first core is smaller than a width in the Y direction of a second beam portion that is the beam portion of the second core,
A power conversion device in which each of the heat dissipation surfaces has a heat dissipation surface extension portion in which the heat dissipation surface is extended on the side of the first beam portion relative to the second beam portion, whose width in the Y direction is increased. The power conversion device according to claim 1, wherein the winding is formed into a curved plate shape on a plane. the magnetic component is made of an insulating resin material and has a coating portion surrounding the winding,
The power conversion device according to claim 1 , wherein the other side in the Z direction of the coating portion is open, and a portion of the winding on the other side in the Z direction is exposed from the coating portion. The power conversion device according to claim 1, wherein the second beam portion and the heat dissipation surface extension portion overlap when viewed in the Z direction. The cooling surface is disposed on the other side of the first core in the Z direction,
an end portion of the first core on the other side in the Z direction and the cooling surface are thermally connected to each other;
The power conversion device according to claim 1 , wherein the heat dissipation portion is a portion of the cooler that protrudes from the cooling surface to one side in the Z direction. a heat sink made of metal and disposed between the winding and the second beam portion;
The power conversion device according to claim 1 , wherein the heat sink is thermally connected to the winding and thermally and electrically connected to the cooler. The power conversion device according to claim 1, wherein one of the first core and the second core is an E-core having a uniform thickness in the Y direction, and the other of the first core and the second core is an I-core having a uniform thickness in at least the Z direction, or one of the first core and the second core is a U-core having a uniform thickness in the Y direction, and the other of the first core and the second core is an I-core having a uniform thickness in at least the Z direction. the heat dissipation portion surrounds an outer circumferential portion of the first core and is provided with a gap between the heat dissipation portion and the outer circumferential portion of the first core,
The power conversion device according to claim 5 , wherein the gap between the outer periphery of the first core and the heat dissipation portion is filled with a thermal conductive material to a height equal to or less than the height of the first beam portion in the Z direction. The power conversion device according to claim 1, wherein one or both of the first core and the second core are U-cores. the magnetic core has one of the legs and a first main leg portion and a second main leg portion that are the main leg portions,
the leg portion, the first main leg portion, and the second main leg portion are arranged in the X direction or in a direction opposite to the X direction in the order of the first main leg portion, the leg portion, and the second main leg portion;
The winding includes a primary winding and a secondary winding, which are transformer windings, wound around the first main leg portion,
The reactor winding is wound around the second main leg portion,
The power conversion device according to claim 1 , wherein a common magnetic path for the primary winding, the secondary winding, and the reactor winding is formed in the leg portion. The power conversion device according to claim 1, wherein the width in the Y direction of the first beam portion of the first core is the same as the width in the Y direction of the main leg portion. a width in the Y direction of the first beam portion of the first core is smaller than a width in the Y direction of the main leg portion and the leg portion,
The power conversion device according to claim 1 , wherein the heat dissipation surface extension portion is provided on a portion of the heat dissipation portion that protrudes toward the first beam portion from a side surface of the heat dissipation portion on the side of the first beam portion. a transformer having a primary winding and a secondary winding;
an inverter circuit having a semiconductor switching element and supplying power to the primary winding;
a rectifier circuit having a plurality of rectifier elements for rectifying the AC voltage output from the secondary winding;
a smoothing reactor having a smoothing capacitor and a reactor winding for smoothing an output of the rectifier circuit;
2. The power conversion device according to claim 1, wherein the primary winding and the secondary winding of the transformer are the windings and the transformer is the magnetic component, or the reactor winding of the smoothing reactor is the windings and the smoothing reactor is the magnetic component. The step-down converter,
each of the plurality of rectifying elements is connected between the other end of the secondary winding and the smoothing reactor;
The power conversion device according to claim 13 , wherein one end of the secondary winding is electrically connected to the heat sink.

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