JP2015109748A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent temperature rise of a power conversion device.SOLUTION: A power conversion device 2 includes a plurality of circuit components, a heat sink 110, and a bus bar 114. The heat sink 110 is thermally coupled to a heating member 108 having such a large heat generation amount so as to have an influence on the other members of the plurality of circuit components. The bus bar 114 electrically connects among the plurality of circuit components. A part of the bus bar 114 is formed so as to cover the heating member 108. At least a part of the bus bar 114 may closely face the heat sink 110.

Description

  The present invention relates to a power conversion device.

  In order to drive a load such as an AC motor, or to convert DC power into AC power and AC power into DC power, a power converter (inverter) is used.

  FIG. 1 is a cross-sectional view illustrating a configuration example of the power conversion device 2r. The power conversion device 2r includes a power module 1022, a capacitor 104, a magnet conductance 106, a heat sink 110, a driver board 120, a controller board 130, a bus bar 101, and the like. In FIG. 1, only some elements are shown for the sake of brevity.

  The power module 102 includes a switching element (hereinafter referred to as a power module) such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor), and the switching element constitutes an arm of the inverter. The capacitor 104 is a smoothing capacitor or a snubber capacitor. The magnet conductance 106 is a relay switch for circuit protection.

  The driver board 120 is mounted with a drive circuit 122 for controlling on / off of the switching element built in the power module 102, that is, a gate voltage. On the controller board 130, a controller (CPU) 132 for controlling the drive circuit 122, the magnet conductance 106, and the like and its peripheral components are mounted.

  Circuit components such as the power module 102, the capacitor 104, and the magnetic conductance 106 are electrically connected via the bus bar 101 or a cable (not shown).

  During operation of the power conversion device 2r, a large current flows through the power module 102, the capacitor 104, and the magnet conductance 106, so that heat generation of those elements becomes a problem. In order to efficiently release the heat generated by the power module 102, the capacitor 104, and the magnet conductance 106 to the outside, these elements are mounted on the heat sink 110 and are thermally coupled. Patent Document 1 discloses a technique related to cooling of a power conversion device.

JP 2000-058746 A

  When the power conversion device 2r of FIG. 1 is mounted on an industrial vehicle used outdoors such as a forklift or a construction machine, the power conversion device 2r is sealed by a housing 140 in order to improve dust resistance and drip resistance. There is a case. In this case, the temperature inside the housing 140 rises due to heat that cannot be released by the heat sink 110. When the temperature inside the housing 140 rises, the characteristics of the power conversion device 2r may deteriorate, or the life thereof may be affected. Even if it is not sealed, there may be a case where the driving motor and its driving device must be arranged close to each other because of space. In this case, the temperature of other devices rises due to the heated air.

  The present inventor has been made in such a situation, and one of exemplary purposes of an aspect thereof is to provide a power conversion device capable of suppressing a temperature rise.

  One embodiment of the present invention relates to a power converter. The power conversion device includes a plurality of circuit components, a heat sink thermally coupled to a heat generating member among the plurality of circuit components, and a bus bar for electrically connecting the plurality of circuit components. The bus bar is formed so as to cover the heat generating member.

  Since the bus bar has a shape covering the heat generating member, the flow of air heated by the heat generating member can be shielded, and the heat of the air can be recovered by the heat sink covering it and released to the heat sink. Moreover, since the diffusion of the heated air is hindered by the heat sink, the temperature distribution in the power converter can be intentionally controlled according to the shape of the heat sink. The heat generating member does not mean a member that generates heat, but a member that generates heat to affect other members, or a member that generates a relatively large amount of heat compared to other members. means.

The bus bar may be in close proximity to the heat sink at least in part.
By making the bus bar and the heat sink close to each other and increasing their thermal coupling coefficient, the heat of the bus bar diffuses to the heat sink in the region where they are close to each other. That is, regarding the heat from the heat generating member, in addition to the path directly conducting from the heat generating member to the heat sink, there is a path indirectly conducting to the heat sink via the bus bar. Therefore, since the heat of the heat generating member can be released to the heat sink by the two paths, the temperature rise of the power conversion device can be suppressed.

  The heat generating member and the bus bar may be electrically connected in a region where they overlap. The bus bar may be in close proximity to the heat sink in a region adjacent to the heat generating member.

The bus bar may be integrally formed so as to cover the upper side and the side of the heat generating member.
The side covered with the bus may be the omnidirectional side of the heat generating member or only in a specific direction. According to this aspect, the heat flow can be blocked by the bus bar, and the heat of the bus bar can be absorbed by bringing the bus bar close to the heat generating member.

The bus bar may have first to fourth surfaces facing the side surfaces of the heat generating member and a fifth surface facing the upper surface of the heat generating member, and may form a closed space around the heat generating member.
In this case, since the air heated by the heat generating member can be confined, the influence of heat on the surrounding members can be suppressed.

  The skirt portion of each of the first surface to the fourth surface may be bent so as to face the heat sink in the vicinity of the heat generating member.

The power conversion device may further include an insulating member having a high heat insulating property provided on the surface side in contact with the space where the heat diffusion of the bus bar should be prevented.
Thereby, it can suppress that the space which should prevent thermal diffusion is heated by the bus bar.

  The bus bar has a laminated structure, and an insulating layer having high thermal conductivity may be inserted between adjacent metal layers. Accordingly, heat can be released to the heat sink not only through the metal layer closest to the heat generating member but also through other metal layers.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature rise of a power converter device can be suppressed.

It is sectional drawing which shows the structural example of a power converter device. It is a circuit diagram showing an example of composition of a power converter. It is a perspective view which shows a part of power converter device of FIG. It is sectional drawing which shows a part of power converter device. It is sectional drawing which shows the whole structure of a power converter device. It is a figure which shows typically the heat flux in the power converter device which concerns on embodiment. It is sectional drawing of the power converter device which concerns on a 1st modification. FIGS. 8A and 8B are perspective views showing a power converter according to a second modification.

  The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  Hereinafter, the power converter device 2 which concerns on embodiment is demonstrated. For example, the power converter 2 is used to drive a load such as a motor. FIG. 2 is a circuit diagram illustrating a configuration example of the power conversion device. The power converter 2 supplies electric power to an electric motor that is a multiphase load, for example, a three-phase load, and controls its rotation.

  The power converter 2 includes a P-pole power supply line 10, an N-pole power supply line 12, a smoothing capacitor 14, power modules 16U to 16W provided for the phases U to W, and drive circuits 18U to 18U provided for the phases U to W. 18W, a plurality of snubber capacitors 20U, 20V, 20W, and a controller 22.

  The smoothing capacitor 14 is provided between the P-pole power supply line 10 and the N-pole power supply line 12 and stabilizes the DC voltage VDC therebetween.

  Each of the power modules 16U to 16W includes a P-pole DC terminal 30, an N-pole DC terminal 32, an AC terminal 34, and a control terminal 36. Each power module 16 includes an upper arm transistor 38 provided between the P-pole DC terminal 30 and the AC terminal 34, and a lower arm transistor 40 provided between the AC terminal 34 and the N-pole DC terminal 32. The upper arm transistor 38 and the lower arm transistor 40 are an FET (Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or a bipolar transistor.

  In the large-capacity power conversion device 2, since a large current flows through the power module, a plurality of power modules 16 are provided for each phase. In FIG. 1, two power modules 16 are provided for each phase. Control electrodes of the upper arm transistor 38 and the lower arm transistor 40 are connected to control terminals 36P and 36N, respectively.

  The snubber capacitor 20 for each phase is provided between the P-pole DC terminal 30 and the N-pole DC terminal 32 of the corresponding power module 16.

  The controller 22 generates control signals S1U to S1W modulated according to the state of the load 4. The drive circuit 18 for each phase drives the upper arm transistor 38 and the lower arm transistor 40 included in the corresponding power module 16 in accordance with the corresponding control signal S1.

  The above is the configuration of the power conversion device 2. In the large-capacity power conversion device 2, a bus bar (also referred to as a bus bar) is used for a path through which a large current flows in order to reduce loss due to wiring resistance. Specifically, P-pole power supply line 10, N-pole power supply line 12, wiring connecting P-pole power supply line 10 and P-pole DC terminal 30, wiring connecting N-pole power supply line 12 and N-pole DC terminal 32, AC The wiring connecting the terminal 34 and the output terminal OUT is formed by a bus bar (114).

  FIG. 3 is a perspective view showing a part of the power converter 2 of FIG. Among the circuit components shown in FIG. 2, the power module 16, the snubber capacitor 20, and the smoothing capacitor 14 are elements (referred to as heat generating members in this specification) 108 that generate a large amount of heat. In addition to these elements, the magnet conductance 106 shown in FIG.

  The heat generating member 108 is thermally and strongly coupled to the heat sink 110. For example, the heat generating member 108 is fixed using screws (not shown) or the like so that the bottom surface thereof is in close contact with the heat sink 110.

  The bus bar 114 is electrically connected to the corresponding electrode 109 of the heat generating member 108. The connection means between the bus bar 114 and the heat generating member 108 is not particularly limited, and may be connected via, for example, a bus bar piece or a screw.

  The bus bar 114 is formed so as to cover the heat generating member 108. The bus bar 114 is in close proximity to the heat sink 110 at least in part (referred to as a thermal coupling portion) 118, and is thermally and strongly coupled to the heat sink 110. The bus bar 114 may be configured by bending a single continuous metal plate, or may be configured by combining a plurality of metal plates.

  The bus bar 114 is integrally formed so as to cover the upper side and the side of the heat generating member 108. More specifically, the bus bar 114 has a first surface S11 to a fourth surface S14 that face the side surface of the heat generating member 108, and a fifth surface S15 that faces the upper surface of the heat generating member 108. A closed space is formed around 108. In other words, the heat generating member 108 is substantially sealed by the bus bar 114 and the heat sink 110.

  Further, in order to increase the thermal coupling coefficient between the bus bar 114 and the heat sink 110, the skirt portions of the first surface S11 to the fourth surface S14 are arranged in the four regions 118 adjacent to the heat generating member 108 with the heat sink 110. It is bent so as to face each other.

FIG. 4 is a cross-sectional view showing a part of the power conversion device 2.
The heat sink 110 is made of a material having high thermal conductivity such as aluminum. Since aluminum has electrical conductivity, it cannot be brought into direct contact with the bus bar 114. Therefore, it is preferable that the bus bar 114 and the heat sink 110 are in close contact with each other through the insulating member 150 having high thermal conductivity in the heat coupling portion 116. Examples of the insulator having a high thermal conductivity include ceramics such as alumina, a resin mixed with a thermal conductive filler, and the like.

  In addition, when the bus bar 114 and the heat sink 110 may be at the same potential, the bus bar 114 and the heat sink 110 may be directly brought into close contact with each other without the insulating member 150 interposed therebetween.

 In the power conversion device 2, when the temperature of the driver board 120 or the controller board 130 rises, the performance of the power conversion device 2 may deteriorate. Therefore, as shown in FIG. 1, when the driver board 120 and the controller board 130 are disposed above the heat generating member 108, it is desirable to shield heat from the heat generating member 108 upward. From this point of view, the bus bar 114 is formed so as to cover at least the upper surface of the heat generating member 108.

  Further, the heat generated by the heat generating member 108 adversely affects circuit components other than the driver board 120 and the controller board 130 disposed on the heat sink 110. From this point of view, in order to shield the heat escaping from the heat generating member 108 in the lateral direction, the bus bar 114 is formed to cover the side surface in addition to the upper surface of the heat generating member 108. That is, the bus bar 114 covers a surface other than the bottom surface of the heat generating member 108, that is, the side surface and the top surface, as shown in FIG.

  The heat generating member 108 has an electrode 109 (connection terminal) provided on the upper surface thereof. The heat generating member 108 and the bus bar 114 are electrically connected via a conductive screw 115 or bus bar piece in a region where they overlap. The bus bar 114 is in close proximity to the heat sink 110 in a region 118 adjacent to the heat generating member 108.

  In order to prevent the heat from the heating member 108 from diffusing into the space where the circuit components adjacent to it, the driver board 120 and the controller board 130 are arranged, the bus bar 114 should be covered at least partially or entirely. It is preferable to provide a heat insulating member 116 having high heat insulating properties. When attention is paid to one heat generating member 108, the heat insulating member 116 is inserted between a space where circuit components adjacent to the heat generating member 108, the driver board 120, the controller board 130, and the like are arranged, and the bus bar 114. The bus bar 114 and the heat insulating member 116 may be in close contact with each other or may be disposed apart from each other. In particular, since the driver board 120, the controller board 130, and the like are members that should be avoided from heating, it can be said that the space surrounded by the housing 140 in which they are arranged is a region where heat diffusion should be prevented. It can be understood that the heat insulating member 116 partitions the space where heat diffusion should be prevented and the space where the heat generating member 108 is disposed in a heat insulating state.

FIG. 5 is a cross-sectional view showing the overall configuration of the power conversion device 2.
The power module 102, the capacitor 104, the magnet conductance 106, and the like correspond to the heat generating member 108 described above. The power module 102, the capacitor 104, and the magnet conductance 106 are electrically connected via some bus bars 114. The bus bar 114 is formed so as to cover each of the heat generating members 108. Of course, circuit components such as the heat generating member 108 and the driver board 120 and the controller board 130 are also connected via a bus bar and a cable (not shown).

The above is the configuration of the power conversion device 2. Next, the advantages will be described.
FIG. 6 is a diagram schematically showing the heat flux in the power conversion device 2 according to the embodiment. The arrows in the figure indicate heat flux. Part of the heat generated by the heat generating member 108 flows from the bottom surface toward the heat sink 110. Further, the heat generated from the heat generating member 108 on the upper surface or the side surface thereof is conducted through the bus bar 114 and flows into the heat sink 110 at the heat coupling portion 118. Since the upper surface side of the bus bar 114 is covered with the heat insulating member 116, the heat of the bus bar 114 is not transmitted to the space 152 but is confined in the space 154 surrounded by the bus bar 114.

  According to the power conversion device 2, it is possible to suppress a temperature rise in the space 152 inside the housing 140 due to heat generated by the heat generating member 108, particularly a temperature rise in the space where the driver board 120 and the controller board 130 are arranged. it can. Moreover, since the temperature rise of the space 154 around the heat generating member 108 is also suppressed, the device temperature of the heat generating member 108 can be lowered than before. Thereby, the performance of the power converter device 2 can be improved.

  Furthermore, conventionally, various heat countermeasures such as water cooling and air cooling by a fan have been required to suppress temperature rise. In the power conversion device 2 according to the embodiment, since the cooling by the bus bar 114 is effective, water cooling becomes unnecessary and the number of fans can be reduced.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and various modifications may exist in each of those constituent elements, each processing process, and a combination thereof. Hereinafter, such modifications will be described.

(First modification)
FIG. 7 is a cross-sectional view of the power converter 2 according to the first modification. In general, the circuit element is connected to a plurality of wirings having different potentials. Therefore, each heating member 108 is often connected to a plurality of bus bars. Therefore, in this modification, the bus bar 114 has a stacked structure including a plurality of metal layers 160 and 162 and an insulating layer 164.

  For example, the case where the heating member 108 is the snubber capacitor 20U of FIG. 2 will be described. Snubber capacitor 20 </ b> U is electrically connected to first metal layer 160 corresponding to P-pole power supply line 10 and second metal layer 162 corresponding to N-pole power supply line 12.

  The insulating layer 164 is inserted between the adjacent metal layer 160 and the metal layer 162. The insulating layer 164 is preferably formed using a material having high thermal conductivity.

  According to this modified example, heat can be released to the heat sink 110 not only through the metal layer 160 closest to the heat generating member 108 but also through the other metal layer 162 and the insulating layer 164, so that the heat conduction path It is possible to further reduce the thermal resistance and increase the cooling efficiency.

(Second modification)
FIGS. 8A and 8B are perspective views showing power converters 2a and 2b according to a second modification. In these modifications, the shape of the bus bar 114 is different from that of FIG.
In the power conversion device 2a of FIG. 8A, the bus bar 114 does not completely seal the heat generating member 108, but its side surface is open. Also in this modification, the bus bar 114 is integrally formed so as to cover the upper side and the side of the heat generating member 108. For example, when the space where temperature rise should be suppressed exists only above the heat generating member 108 and the temperature rise of the side surface of the heat generating member 108 is allowed, or the space of the side surface of the heat generating member 108 has thermal conductivity. When a cooling body having a high temperature is disposed, the bus bar 114 may be opened to a space where the temperature rise is allowed.

  In the modification of FIG. 8B, the bus bar 114 that covers the heat generating member 108 is divided into two bus bar pieces 114a and 114b. When the wiring path for connecting the plurality of circuit elements becomes complicated, the wiring efficiency can be improved by covering the heat generating member 108 by combining the plurality of bus bars 114 in this way.

  Further, as shown in FIG. 8B, a plurality of heat generating members 108 may be covered using a single bus bar 114. In other words, a plurality of heat generating members 108 may be arranged in the space 154 surrounded by the bus bar 114.

(Third Modification)
If there is a gap between the inner wall of the bus bar 114 and the heat generating member 108, the thermal resistance between the bus bar 114 and the heat generating member 108 increases due to air. Therefore, the bus bar 114 may be configured to be in close contact with the heat generating member 108 directly or through a material having low thermal conductivity. Alternatively, the bus bar 114 and the heat generating member 108 may be connected by a metal piece that forms a heat bridge.

Finally, the use of the power conversion device 2 will be described.
The present invention is particularly effective in the power conversion device 2 having a sealed structure using a casing. For example, the power converter 2 is suitable for vehicles and devices that are used outdoors and require dustproof and dripproof (or waterproof), such as industrial vehicles such as forklifts and construction machinery. However, the power conversion device 2 can be used for various applications other than these.

  Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate the principles and applications of the present invention, and the embodiments are defined in the claims. Many variations and modifications of the arrangement are permitted without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 2 ... Power converter device, 4 ... Load, 102 ... Power module, 104 ... Capacitor, 106 ... Magnet conductance, 108 ... Heat generating member, 110 ... Heat sink, 112 ... Screw, 114 ... Bus bar, 116 ... Thermal insulation member, 118 ... Thermal coupling Part: 120 ... Driver board 122: Drive circuit 130 ... Controller board 132 ... Controller 140 ... Housing 150 ... Insulating member 152, 154 ... Space 160 ... First metal layer 162 ... Second metal layer DESCRIPTION OF SYMBOLS 164 ... Insulating layer, 10 ... P pole power line, 12 ... N pole power line, 14 ... Smoothing capacitor, 15 ... Power module group, 16 ... Power module, 18 ... Drive circuit, 20 ... Snubber capacitor, 22 ... Controller, 30 ... P pole DC terminal, 32 ... N pole DC terminal, 34 ... AC terminal, 36 ... Control terminal, 3 ... upper arm transistor, 40 ... lower arm transistor.

Claims (12)

Multiple circuit components,
A heat sink thermally coupled to a heat generating member of the plurality of circuit components;
A bus bar for electrically connecting the plurality of circuit components;
With
The bus bar is formed so as to cover the heat generating member.   The power converter according to claim 1, wherein at least a part of the bus bar is in close proximity to the heat sink. The heat generating member and the bus bar are electrically connected in a region where they overlap,
The power converter according to claim 2, wherein the bus bar is in close proximity to the heat sink in a region adjacent to the heat generating member.   4. The power converter according to claim 1, wherein the bus bar is integrally formed so as to cover an upper side and a side of the heat generating member. 5. The bus bar is
First to fourth surfaces facing side surfaces of the heat generating member;
A fifth surface facing the upper surface of the heat generating member;
The power conversion device according to claim 1, wherein a closed space is formed around the heat generating member.   6. The power conversion device according to claim 5, wherein a skirt portion of each of the first surface to the fourth surface is bent so as to be in close proximity to the heat sink in a region adjacent to the heat generating member.   The electric power according to claim 1, wherein the bus bar has a laminated structure, and an insulating layer having high thermal conductivity is inserted between adjacent metal layers. Conversion device.   The power converter according to claim 1, wherein a part of the bus bar and the heat sink are thermally coupled via an insulating member having high thermal conductivity.   The power converter according to claim 1, wherein the heat generating member includes at least one of a power module, a capacitor, and a magnet conductor. The heat generating member includes any one of a power module, a capacitor, and a magnet conductor,
9. The power conversion according to claim 1, wherein a member that generates a relatively small amount of heat with respect to the heat generating member of the plurality of circuit components is not covered with the bus bar. apparatus.   11. The power conversion device according to claim 1, wherein the heat generating member is substantially sealed by the bus bar and the heat sink.   The power conversion device according to any one of claims 1 to 11, further comprising an insulating member having a high heat insulating property provided on a surface side of the bus bar in contact with a space where heat diffusion is to be prevented.

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