Power converter

Abstract

To provide a power conversion device and a coil unit in which a coil can be further cooled.SOLUTION: A power conversion device according to the present disclosure includes a casing having a main body part in which a housing space is defined and a refrigerant flow path formed in the main body part, a coil unit that is disposed in the housing space and is cooled by a refrigerant flowing through the refrigerant flow path, and a power conversion circuit that is disposed in the housing space and is electrically connected to the coil unit. The coil unit includes a coil case that is formed of a heat conductive material, a coil that has a core disposed in the coil case and a winding part having a portion between one end and the other end connected to the power conversion circuits wound around the core, and an insulating part that is disposed in the coil case and electrically insulates the coil case from the coil. The main body part has an opening portion that opens a portion of the refrigerant flow path to the housing space. The coil case is fixed to the body part so as to close the opening portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device Place . [Background Art]

[0002] Patent Document 1 discloses a coil cooling structure including: first and second circular coils wound around a core; a casing that accommodates the coils; and a cooling member which is disposed in a space with a substantially triangular cross-section formed between the coils and the casing and has a cooling medium passage formed therein. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-156678 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] By the way, in the field of power conversion devices, there is a growing momentum for downsizing the entire device in order to increase added value. Along with this trend, there is a demand for downsizing coils in the device. However, as coils are downsized, the heat generation density increases due to the self-heating of the coil itself, which poses a problem.

[0005] The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a power conversion device Place capable of better cooling a coil. [Means for Solving the Problem]

[0006] To solve the above problems, the power conversion device according to the present disclosure comprises a main body that defines an internal housing space, and a casing having a refrigerant flow path formed in the main body; a coil unit disposed in the housing space and cooled by a refrigerant flowing through the refrigerant flow path; and a power conversion circuit disposed in the housing space and electrically connected to the coil unit. The coil unit comprises a coil case formed of a thermal conductive material, a core disposed in the coil case, and a coil having a winding portion in which the portion between one end connected to the power conversion circuit and the other end is wound around the core; and an insulating portion disposed in the coil case that electrically insulates the coil case from the coil coil. The main body has an opening that opens a part of the refrigerant flow path to the housing space, and the coil case is fixed to the main body so as to close the opening. [Effects of the Invention]

[0008] According to this disclosure, a power conversion device capable of cooling coils more effectively Place We can provide this. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a schematic cross-sectional view of the power conversion device according to an embodiment of the present disclosure. [Figure 2] This is a view of the coil unit from the direction of line II-II in Figure 1. [Figure 3] This figure shows a cross-sectional view of a coil unit according to another embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] The power conversion device according to the embodiment of this disclosure will be described below with reference to the attached drawings.

[0011] <Embodiment of a power converter> A power converter is a device that converts, for example, direct current power to three-phase alternating current power. Examples of power converters include inverters used in power grids such as those in power plants, and inverters used to drive AC rotating electric machines (motors) in electric vehicles. As shown in Figure 1, the power converter 100 comprises a casing 1, a power conversion circuit 2, and a coil unit 3.

[0012] (Casing) Casing 1 is an enclosure for housing the elements (power conversion circuit 2, coil unit 3) that constitute the power conversion device 100. In this embodiment, casing 1 cools the coil unit 3 using a liquid coolant R supplied from outside casing 1. Casing 1 has a main body 10 and a coolant flow path 11.

[0013] (Main body) The main body 10 defines an internal containment space S in which each of the above elements is arranged. The main body 10 is formed of, for example, a metal material. However, the material forming the main body 10 is not limited to a metal material, and may be, for example, a synthetic resin material.

[0014] (Refrigerant flow path) The refrigerant flow path 11 is a passage through which the liquid refrigerant R described above flows. In this embodiment, the liquid refrigerant R is, for example, water. However, a liquid other than water may be used for the liquid refrigerant R. The refrigerant flow path 11 is formed in the main body 10. Specifically, the refrigerant flow path 11 is formed to extend inside a portion of the wall portion that constitutes the main body 10.

[0015] Furthermore, lines L1 and L2, which connect to a refrigerant supply device located outside the power converter 100, are connected to one end and the other end of the refrigerant flow path 11 that opens to the outer surface of the main body 10. Liquid refrigerant R that flows into the refrigerant flow path 11 from one end of the refrigerant flow path 11 through line L1 flows through the refrigerant flow path 11, then flows out to line L2 from the other end of the refrigerant flow path 11, and returns to the refrigerant supply device through line L2.

[0016] Further, the main body portion 10 according to the present embodiment has an opening 10h that opens a part of the refrigerant flow path 11 to the accommodation space S between one end and the other end of the refrigerant flow path 11.

[0017] (Power Conversion Circuit) The power conversion circuit 2 is a circuit that converts electric power input from the outside of the power conversion device 100. The power conversion circuit 2 is accommodated in the main body portion 10 of the casing 1. That is, the power conversion circuit 2 is disposed in the accommodation space S. The power conversion circuit 2 includes, for example, a power supply (not shown) for performing an operation of converting input electric power (for example, the operation of a control device and a switching operation of a power semiconductor element or the like). Further, for example, a bus bar or the like (not shown) serving as a current input / output terminal (a conductor for connection) is electrically connected to the power conversion circuit 2.

[0018] (Coil Unit) The coil unit 3 is electrically connected to the power conversion circuit 2. The coil unit 3 is accommodated in the main body portion 10 of the casing 1. That is, the coil unit 3 is disposed in the accommodation space S. As shown in FIG. 1 and FIG. 2, the coil unit 3 includes a coil case 30, a sealing body 31, a coupler 32, a coil 33, a first heat transfer portion 34, a second heat transfer portion 35, and an insulating portion 36.

[0019] (Coil Case) The coil case 30 is a casing for accommodating elements constituting the coil unit 3 (the coil 33, the first heat transfer portion 34, the second heat transfer portion 35, and the insulating portion 36) inside thereof. The coil case 30 is formed of a heat conductive material. As the heat conductive material herein, for example, a metal material including aluminum or the like is employed. A material other than aluminum may be employed as the heat conductive material for forming the coil case 30. The coil case 30 is formed of a plurality of wall portions. The coil case 30 has a bottom wall portion 30a and a side wall portion 30b.

[0020] The bottom wall portion 30a has a flat plate shape. The bottom wall portion 30a is fixed to the main body portion 10 so as to close an opening formed in the main body portion 10. Accordingly, the liquid refrigerant R flowing through the refrigerant flow path 11 contacts the bottom wall portion 30a from the opposite side to the accommodation space S. The bottom wall portion 30a is fixed to the inner surface of the main body portion 10 that defines the accommodation space S, for example, by a plurality of coupling members 32 spaced apart from each other along the outer edge of the main body portion 10. For the coupling member 32, a member such as a fastener or a bolt is employed, for example. In FIGS. 1 and 2, a bolt is shown as an example.

[0021] Further, a sealing body 31 is disposed between the bottom wall portion 30a and the main body portion 10. The sealing body 31 has, for example, an annular shape along the outer edge of the main body portion 10, and is disposed between the coupling member 32 and the refrigerant flow path 11 in the direction in which the flat-shaped bottom wall portion 30a extends, between the bottom wall portion 30a and the main body portion 10. The sealing body 31 is in contact with the bottom wall portion 30a and the main body portion 10, and is sandwiched between the bottom wall portion 30a and the main body portion 10. For the sealing body 31, for example, an O-ring or the like is employed.

[0022] The side wall portion 30b has a flat plate shape. The side wall portion 30b is provided integrally with the bottom wall portion 30a so as to rise from the bottom wall portion 30a. In the present embodiment, four side wall portions 30b are provided on the bottom wall portion 30a, and these four side wall portions 30b together with the bottom wall portion 30a define a space for accommodating the core 33a (described later) of the coil 33. In FIG. 1, only the cross-section of two side wall portions 30b is illustrated for convenience of illustration. Among the four side wall portions 30b that define the space for accommodating the core 33a of the coil 33, two adjacent side wall portions 30b are integrally connected to each other (see FIG. 2). In the present embodiment, these four side wall portions 30b and one bottom wall portion 30a define a rectangular parallelepiped space. The space is open toward the opposite side from the bottom wall portion 30a.

[0023] (Coil) Coil 33 is a reactor electrically connected to the power supply of the power conversion circuit 2. In this embodiment, coil 33 is a common-mode coil for the power supply. Coil 33 has a core 33a and a winding portion 33b.

[0024] The core 33a is a toroidal core located inside the coil case 30. The core 33a is positioned so as not to be in contact with the inner surface of the coil case 30. The core 33a is a ferromagnetic material formed from a metallic material, such as iron. The core 33a is cylindrical with its central axis Ar. The core 33a has an outer circumferential surface 33s1 that faces the inner surface of the side wall portion 30b inside the coil case 30, and an inner circumferential surface 33s2 that faces inward inside the coil case 30. Both the outer circumferential surface 33s1 and the inner circumferential surface 33s2 are cylindrical surfaces. The coil case 30 that houses the core 33a is fixed to the inner surface of the main body portion 10 from the direction in which the central axis Ar extends.

[0025] The winding portion 33b is, for example, a conductor with one end and the other end connected to the power supply of the power conversion circuit 2. The portion of the winding portion 33b between the one end and the other end is wound around the core 33a. In this embodiment, the winding portion 33b is wound around the core 33a in a cancellation winding manner. However, the winding method of the winding portion 33b around the core 33a is not limited to cancellation winding, and may also be bifilar winding or the like.

[0026] The winding portion 33b is positioned so as not to contact the inner surface of the coil case 30. The winding portion 33b is formed of a metallic material, such as copper. In this embodiment, two winding portions 33b are wound around the core 33a. As shown in Figure 2, the portions of each of the two winding portions 33b wound around the core 33a are spaced apart from each other with the central axis Ar in between. The portions of the winding portion 33b that are not wound around the core 33a extend from the core 33a toward the power conversion circuit 2 through an opening in the coil case 30.

[0027] (First heat transfer section) The first heat transfer section 34 is located inside the core 33a within the coil case 30. In this embodiment, the first heat transfer section 34 extends in a cylindrical shape around the central axis Ar. Specifically, the first heat transfer section 34 is positioned to penetrate the inside of the core 33a in the direction in which the central axis Ar extends. The outer circumferential surface of the first heat transfer section 34 and the inner circumferential surface 33s2 of the core 33a are separated and facing each other in the direction in which the bottom wall 30a expands. One end face of the first heat transfer section 34 (one side in the direction in which the central axis Ar extends, the lower side in Figure 1) is connected to (in contact with) the bottom wall 30a.

[0028] The first heat transfer section 34 is formed of a thermal conductive material. The thermal conductive material may be a metal material, such as aluminum. However, materials other than aluminum may be used for the thermal conductive material forming the first heat transfer section 34. Preferably, the first heat transfer section 34 is formed of a thermal conductive material with a higher thermal conductivity than the thermal conductive material forming the coil case 30.

[0029] (Second heat transfer section) The second heat transfer section 35 is located outside the core 33a within the coil case 30. The second heat transfer section 35 is positioned between the coil case 30 and the core 33a. In this embodiment, the second heat transfer section 35 has an inner circumferential surface 35s1 that forms a cylindrical surface along the outer circumferential surface 33s1 of the core 33a, and an outer circumferential surface 35s2 that faces the inner surface of the side wall 30b. The inner circumferential surface 35s1 of the second heat transfer section 35 faces the outer circumferential surface 33s1 of the core 33a in the direction in which the bottom wall 30a expands. The inner circumferential surface 35s1 of the second heat transfer section 35 and the outer circumferential surface 33s1 of the core 33a face each other with a gap in the direction in which the bottom wall 30a expands.

[0030] In this embodiment, the second heat transfer section 35 has a shape in which a cylindrical portion is hollowed out from the central part of a rectangular parallelepiped-shaped member. The inner circumferential surface 35s1 of the second heat transfer section 35 is formed by hollowing out the cylindrical portion from the rectangular parallelepiped-shaped member. The outer circumferential surface 35s2 of the second heat transfer section 35 is in contact with the inner surface of the coil case 30. One end face of the second heat transfer section 35 (one side in the direction in which the central axis Ar extends, the lower side in Figure 1) is connected to (in contact with) the bottom wall portion 30a.

[0031] The second heat transfer section 35 is formed of a thermal conductive material. The thermal conductive material here may be a metallic material, such as aluminum. However, materials other than aluminum may be used for the thermal conductive material forming the second heat transfer section 35. It is preferable that the second heat transfer section 35 is formed of a thermal conductive material with a higher thermal conductivity than the thermal conductive material forming the coil case 30. In this embodiment, the second heat transfer section 35 is formed of the same material as the first heat transfer section 34, for example.

[0032] (Insulation part) The insulating portion 36 is an insulating member that electrically insulates the elements (coil 33, first heat transfer portion 34, second heat transfer portion 35) housed in the coil case 30 from each other, and also electrically insulates each of these elements from the coil case 30. The insulating portion 36 is located inside the coil case 30. The insulating portion 36 is positioned to fill the gaps between the coil 33 and the coil case 30, the gap between the coil 33 and the first heat transfer portion 34, and the gap between the coil 33 and the second heat transfer portion 35. Therefore, the insulating portion 36 electrically insulates the coil 33 and the coil case 30, the coil 33 and the first heat transfer portion 34, and the coil 33 and the second heat transfer portion 35 from each other.

[0033] In this embodiment, the insulating portion 36 is formed of a potting material. Liquid potting material is filled into the inside of the coil case 30 from the outside (potting), and the filled potting material seals each element that is exposed in the space inside the coil case 30. The potting material filled into the inside of the coil case 30 hardens over a predetermined period of time to form an insulating portion 36, which electrically insulates the elements inside the coil case 30 and the space outside the coil case 30 from each element. For example, insulating materials such as silicone gel or epoxy resin are used as the potting material. That is, the insulating portion 36 is formed of an insulating material such as silicone gel or epoxy resin. Note that synthetic resins other than silicone gel or epoxy resin may be used as the potting material.

[0034] (Effects / Actions) When power is input to the power conversion circuit 2 and current flows through the winding portion 33b of the coil unit 3, the core 33a of the coil 33 generates heat. The heat generated from the core 33a is conducted through the insulating portion 36 to the coil case 30, which is made of a thermal conductive material. The heat conducted to the coil case 30 is conducted through the coil case 30 toward the main body portion 10 of the casing 1 and reaches the portion that closes the opening 10h that opens the refrigerant flow path 11. Since the portion that closes the opening of the refrigerant flow path 11 is actively subjected to heat exchange by the liquid refrigerant R, the heat conducted to that portion is removed by the liquid refrigerant R flowing through the refrigerant flow path 11.

[0035] In the configuration described above, the coil case 30, formed of a thermal conductive material, blocks the opening 10h of the main body 10 that opens the refrigerant flow path 11. As a result, the coil case 30 itself is directly cooled by the liquid refrigerant R flowing through the refrigerant flow path 11. In other words, the coil case 30 also serves as a heat sink for the coil unit 3. This reduces the number of components to which heat generated from the core 33a of the coil 33 is conducted, compared to, for example, a separate heat sink for cooling the coil case 30. Therefore, the heated coil 33 can be cooled more effectively. Consequently, the coil 33 can be made smaller. Furthermore, since a heat sink or similar is not required to cool the coil unit 3, the entire power conversion device 100 can be designed to be more compact.

[0036] Furthermore, the inventors discovered that the surface temperature of core 33a (toroidal core) is uniformly distributed in the circumferential direction around the central axis Ar. In the configuration described above, the coil case 30 housing the core 33a is fixed to the inner surface of the main body 10 from the direction in which the central axis Ar extends. This makes it less likely for there to be a difference in the length of the heat path conducted from the core 33a to the coil case 30 in the circumferential direction around the central axis Ar. In other words, the heat generated from the core 33a is less likely to be unevenly distributed within the coil case 30. Therefore, the core 33a can be cooled more uniformly.

[0037] Furthermore, in the above-described configuration, a cylindrical first heat transfer section 34 centered on the central axis Ar is positioned inside the core 33a, and this first heat transfer section 34 is connected to the portion of the coil case 30 that closes the opening 10h. This allows heat generated from the inner portion of the core 33a to be smoothly conducted towards the coil case 30, compared to, for example, a case where an insulating section 36 or the like is simply positioned inside the core 33a (the region surrounded by the inner circumferential surface 33s2 of the core 33a inside the coil case 30). In other words, heat generated from the core 33a can be smoothly dissipated to the coil case 30. Therefore, the coil 33 can be cooled more effectively.

[0038] Furthermore, in the above-described configuration, the second heat transfer section 35, positioned between the coil case 30 and the core 33a, has an inner circumferential surface 35s1 that forms a cylindrical surface along the outer circumferential surface 33s1 of the core 33a. As a result, compared to, for example, a case where the coil unit 3 does not have the second heat transfer section 35, heat generated from the outer circumferential surface 33s1 of the core 33a can be conducted to the coil case 30 via the inner circumferential surface 35s1 of the second heat transfer section 35. In other words, heat generated from the core 33a can be smoothly dissipated to the coil case 30. Therefore, the coil 33 can be cooled more effectively.

[0039] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to that of the embodiments, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the gist of this disclosure.

[0040] For example, as shown in Figure 3, the coil unit 3 may further have a heat dissipation section 37 provided in the coil case 30 that exchanges heat with the liquid refrigerant R flowing through the refrigerant passage 11. In this case, the heat dissipation section 37 is a fin provided on the bottom wall 30a of the coil case 30 and extending from the bottom wall 30a into the refrigerant passage 11. Multiple heat dissipation sections 37 are arranged in a line at equal intervals in the direction in which the bottom wall 30a widens. The heat dissipation section 37 is formed of a thermal conductive material. Each heat dissipation section 37 may be in the shape of a plate positioned perpendicular to the bottom wall 30a, or it may be in the shape of a column positioned perpendicular to the bottom wall 30a.

[0041] Furthermore, the coil unit 3 does not necessarily have to include the second heat transfer section 35. In this case, for example, the coil case 30 may have an inner surface that forms a cylindrical surface along the outer surface 33s1 of the core 33a. Alternatively, the coil case 30 may be formed in a cylindrical shape.

[0042] <Note> The power conversion device 100 and coil unit 3 described in the embodiment can be understood, for example, as follows.

[0043] (1) The power conversion device 100 according to the first embodiment comprises a main body portion 10 defining an internal containment space S, and a casing 1 having a refrigerant flow path 11 formed in the main body portion 10, a coil unit 3 disposed in the containment space S and cooled by a refrigerant R flowing through the refrigerant flow path 11, and a power conversion circuit 2 disposed in the containment space S and electrically connected to the coil unit 3, wherein the coil unit 3 comprises a coil case 30 made of a thermal conductive material, a core 33a disposed in the coil case 30, and a coil 33 having a winding portion 33b in which the portion between one end and the other end connected to the power conversion circuit 2 is wound around the core 33a, and an insulating portion 36 disposed in the coil case 30 and electrically insulating the coil case 30 and the coil 33, wherein the main body portion 10 has an opening 10h that opens a part of the refrigerant flow path 11 to the containment space S, and the coil case 30 is fixed to the main body portion 10 so as to close the opening 10h.

[0044] As a result, compared to, for example, a case where a separate cooling heat sink is provided in the coil case 30, the number of components to which heat generated from the core 33a of the coil 33 is conducted is reduced. Therefore, the heated coil 33 can be cooled more effectively.

[0045] (2) The power converter 100 according to the second embodiment is the power converter 100 of (1), wherein the core 33a is cylindrical with respect to the central axis Ar, and the coil case 30 may be fixed to the main body 10 from the direction in which the central axis Ar extends.

[0046] This makes it less likely for there to be a difference in the length of the heat path conducted from the core 33a to the coil case 30 in the circumferential direction around the central axis Ar. Therefore, the core 33a can be cooled more uniformly.

[0047] (3) The power converter 100 according to the third embodiment is the power converter 100 of (2), wherein the coil unit 3 further comprises a first heat transfer section 34 formed of a thermal conductive material and extending in a cylindrical shape around the central axis Ar inside the core 33a in the coil case 30, the insulating section 36 further electrically insulates the coil 33 and the first heat transfer section 34, and the first heat transfer section 34 may be connected to a portion of the coil case 30 that closes the opening 10h.

[0048] This allows heat generated from the inner part of the core 33a to be smoothly conducted toward the coil case 30, compared to, for example, a case where an insulating part 36 or the like is simply placed in the part inside the core 33a.

[0049] (4) The power converter 100 according to the fourth embodiment is the power converter 100 of (2) or (3), wherein the coil unit 3 further comprises a second heat transfer section 35 formed of a thermal conductive material and disposed between the coil case 30 and the core 33a, the insulating section 36 further electrically insulates the coil 33 and the second heat transfer section 35, the second heat transfer section 35 has an inner circumferential surface 35s1 that is cylindrical in shape along the outer circumferential surface 33s1 of the core 33a and may be connected to the coil case 30.

[0050] As a result, compared to a case where, for example, the coil unit 3 does not have the second heat transfer section 35, the heat generated from the outer circumferential surface 33s1 of the core 33a can be conducted to the coil case 30 via the inner circumferential surface 35s1 of the second heat transfer section 35. In other words, the heat generated from the core 33a can be smoothly dissipated to the coil case 30.

[0051] (5) The coil unit 3 according to the fifth embodiment comprises a coil case 30 made of a thermal conductive material, a coil 33 having a core 33a disposed inside the coil case 30 and forming a cylindrical shape around a central axis Ar, and a winding portion 33b between one end and the other being wound around the core 33a, a first heat transfer portion 34 made of a thermal conductive material and extending in a cylindrical shape around the central axis Ar inside the core 33a in the coil case 30, and an insulating portion 36 disposed inside the coil case 30 and electrically insulating the coil case 30 and the coil 33 and the coil 33 and the first heat transfer portion 34, wherein the first heat transfer portion 34 is connected to the coil case 30.

[0052] This allows heat generated from the inside of the core 33a to be released to the coil case 30 via the first heat transfer section 34. Therefore, heat generated from the core 33a inside the coil case 30 can be suppressed. As a result, the coil 33 can be cooled more effectively. [Explanation of Symbols]

[0053] 1…Casing 2…Power conversion circuit 3…Coil unit 10…Main body 10h…Opening 11…Refrigerant flow path 30…Coil case 30a…Bottom wall 30b…Side wall 31…Sealing body 32…Coupler 33…Coil 33a…Core 33b…Winding 33s1,35s2…Outer surface 33s2,35s1…Inner surface 34…First heat transfer section 35…Second heat transfer section 36…Insulation section 37…Heat dissipation section 100…Power conversion device Ar…Central axis L1,L2…Lines R…Liquid refrigerant S…Housing space

Claims

1. A casing comprising a main body that defines an internal containment space, and a refrigerant flow path formed in the main body, A coil unit is placed in the aforementioned containment space and is cooled by the refrigerant flowing through the refrigerant passage, A power conversion circuit is arranged in the aforementioned housing space and electrically connected to the coil unit, Equipped with, The coil unit is A coil case formed from a thermal conductive material, A coil comprising a core disposed within the coil case, and a coil having a winding portion wound around the core between one end connected to the power conversion circuit and the other end, An insulating part is disposed inside the coil case and electrically insulates the coil case from the coil, Equipped with, The main body has an opening that causes a part of the refrigerant flow path to open into the containment space, The coil case is fixed to the main body so as to close the opening. Power converter.

2. The aforementioned core forms a ring-shaped structure with respect to its central axis. The coil case is fixed to the main body from the direction in which the central axis extends. The power conversion device according to claim 1.

3. The coil unit is The coil case further comprises a first heat transfer section formed of a thermal conductive material, which extends in a cylindrical shape around the central axis inside the core within the coil case, The insulating part further electrically insulates the coil and the first heat transfer part. The power conversion device according to claim 2, wherein the first heat transfer unit is connected to the portion of the coil case that closes the opening.

4. The coil unit is The device further comprises a second heat transfer section formed of a thermal conductive material and positioned between the coil case and the core, The insulating part further electrically insulates the coil and the second heat transfer part. The second heat transfer section has an inner surface that forms a cylindrical surface along the outer surface of the core and is connected to the coil case. The power conversion device according to claim 2 or claim 3.

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