JP2016063668A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of heat generated in a conductive member by flowing a large current upon members constituting a power conversion apparatus.SOLUTION: The power conversion apparatus includes: a plurality of power semiconductor modules; a capacitor; and a conductive member for connecting the plurality of power semiconductor modules to the capacitor. The conductive member includes a first conductive member and a second conductive member connected to the capacitor, composed of a material different from that of the first conductive member and having conductivity smaller than that of the first conductive member. The first conductive member includes: a body section forming a connection part for connecting with the second conductive member; a first connection terminal formed in a width narrower than a width of the body section and connected to a DC terminal of either one of the plurality of power semiconductor modules; and a second connection terminal formed in a width narrower than the width of the body section and connected to the DC terminal of the power semiconductor module.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device used for a hybrid vehicle or a plug-in hybrid vehicle electric vehicle.

  In recent years, the demand for higher output of hybrid vehicles has increased, and it is necessary to pass a large current through a power converter that supplies an alternating current to a drive motor. The power conversion device includes a conductor member that transmits a large current. The inverter conductor portion shown in Patent Document 1 is formed of a conductor member 800, and connects the power module and the capacitor with a material having high conductivity such as copper, for example.

  However, since an area projected onto the upper surfaces of the power module and the capacitor is required, this is a cause of weight increase in reducing the size and weight of the product.

  We also want to reduce the amount of copper used in order to reduce costs. Alternatively, the area should be as small as possible, or replacement with an alternative material (for example, aluminum) is necessary.

  However, near the portion of the conductor member connected to the power module, the width of the conductor member is limited, so that current concentration occurs and the amount of heat generation increases. I would like to replace the conductor member with lightweight and inexpensive aluminum as an alternative material, but there are places where the replacement is not possible for the reasons described above.

JP 2014-82822

  The subject of this invention is reducing the influence on the member which comprises a power converter device with the heat which generate | occur | produced in the conductor member through which a large electric current flows.

  In order to solve the above problems, a power conversion device according to the present invention includes a plurality of power semiconductor modules, a capacitor that smoothes DC power, and a conductor member that connects the plurality of power semiconductor modules and the capacitor. The conductor member is composed of a first conductor member connected to the plurality of power semiconductor modules and a material that is connected to the capacitor and is different from the first conductor member, and more than the first conductor member. A second conductor member having low conductivity, and the first conductor member has a main body part that forms a connection part for connecting to the second conductor member, and a width smaller than the width of the main body part. A first connection terminal that is formed and connected to a DC terminal of any one of the plurality of power semiconductor modules, and is formed with a width smaller than the width of the main body and the front And a second connection terminal connected to a DC terminal of the power semiconductor module different from the power semiconductor module connected to the first connection terminal.

  By this invention, the influence of the heat to the member which comprises a power converter device can be reduced.

It is an expanded perspective view of the power converter device 200 concerning this embodiment. FIG. 6 is an enlarged perspective view of a conductor member 801. 7 is a perspective view of a first mold bus bar 801 excluding a mold material 851. FIG. FIG. 3 is a cross-sectional view of the first mold bus bar 801 as seen from the direction of the arrow on the plane A in FIG. 2, the upper diagram is before molding with the molding material, and the lower diagram is after molding with the molding material. FIG. 10 is a cross-sectional view regarding a joining configuration of a first conductor member 810 and a second conductor member 820 according to another embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of a power conversion device 200 according to this embodiment. FIG. 2 is a perspective view of the first molded bus bar 801. FIG. 3 is a perspective view of the first mold bus bar 801 excluding the mold material 851.

  The housing 220 houses or supports the power semiconductor modules 300a to 300c, the capacitor module 500, the first molded bus bar 801, the second molded bus bar 802, and the circuit board 20. The casing 220 is made of metal, for example, aluminum alloy.

  The power semiconductor modules 300a to 300c convert a direct current into an alternating current and output a U-phase alternating current, a V-phase alternating current, and a W-phase alternating current, respectively. Each of the power semiconductor modules 300a to 300c has a power module terminal 302. The power module terminal 302 is connected to the first molded bus bar 801 or the second molded bus bar 802 and transmits a direct current.

  Capacitor module 500 smoothes DC power. Capacitor terminal 701 is connected to first molded bus bar 801 or second molded bus bar 802.

  The first molded bus bar 801 and the second molded bus bar 802 are connected to the power module terminal 302 and the capacitor terminal 701, and function as relay conductors that transmit a direct current between the power semiconductor modules 300a to 300c and the capacitor module 500.

  In the present embodiment, the first molded bus bar 801 functions as a DC relay conductor on the positive electrode side, and the second molded bus bar 802 functions as a DC relay conductor on the negative electrode side.

  As shown in FIG. 2, the first mold bus bar 801 has a mold material 851, and the mold material 851 functions as a member for fixing to the housing 220. Similarly, the second mold bus bar 802 includes a mold material 852, and the mold material 852 functions as a member for fixing to the housing 220.

  The circuit board 20 is disposed on the metal board base 11 in order to reduce the influence of noise and to remove heat from the element heat generation.

  As shown in FIG. 3, the first molded bus bar 801 includes a first conductor member 810 and a second conductor member 820. The first conductor member 810 is provided with a first connection portion 814, and the second conductor member 820 is provided with a second connection portion 822. The first conductor member 810 is connected to the second conductor member 820 by joining the first connection portion 814 and the second connection portion 822. The first connection portion 814 and the second connection portion 822 are joined by a method such as FSW.

  The second conductor member 820 is made of a material different from that of the first conductor member 810 and has a volume larger than that of the first conductor member 810. For example, the first conductor member 810 is made of a copper material having excellent conductivity, and the second conductor member 820 is made of an aluminum material having excellent weight reduction. The second conductor member 820 has a capacitor side connection terminal 821 connected to the capacitor terminal 701.

  The first conductor member 810 includes a main body portion 815 that forms the first connection portion 814, a first connection terminal 811, a second connection terminal 812, and a third connection terminal 813. The first connection terminal 811 is connected to the main body 815 and to the power semiconductor module 300a. Further, the width f of the first connection terminal 811 is formed smaller than the width F of the main body 815. Similarly, the second connection terminal 812 is connected to the main body 815 and to the power semiconductor module 300b. Further, the width f of the second connection terminal 812 is formed smaller than the width F of the main body 815. The same applies to the third connection terminal 813.

  Since the main body portion 815 functions as a member that connects the first connection terminal 811, the second connection terminal 812, and the third connection terminal 813, the return current easily flows when the power semiconductor modules 300 a to 300 c are operating. It is a place where fever is likely to occur. Therefore, the first conductor member 810 having the main body 815 is made of a copper material having excellent conductivity, and the second conductor member 820 is made of an aluminum material having lower conductivity than the copper material.

  As a result, the second conductor member 820 is less likely to flow current than the first conductor member 810, and the heat generated by the reflux current is less likely to be transmitted to the second conductor member 820. Accordingly, there is an effect of suppressing heat input to the capacitor module 500 connected to the second conductor member 820.

  As can be seen by comparing FIG. 2 and FIG. 3, the first connection portion 814 and the second connection portion 822 are covered with a molding material 851. Accordingly, the first connecting member 814 and the second connecting member 822 are prevented from cracking or peeling off against twisting or warping of the first conductor member 810 and the second conductor member 820, and the molding material 851 has a reinforcing role. .

  Further, by providing a certain number or more of screwing points at the four corners of the molding material 851 or at the side of the joint portion, connection is made to the housing 220, and when vibration is applied, the first conductor member 810 and the second conductor member 820 are connected. This prevents damage due to the phenomenon of vibration and warpage. As a result, reliability against external force such as vibration can be ensured.

  4 is a cross-sectional view of the first mold bus bar 801 as seen from the direction of the arrow on the plane A in FIG. 2, the upper diagram is before molding with the molding material, and the lower diagram is after molding with the molding material. .

  By forming the end shape (first connection portion 814 and second connection portion 822) of each of the first conductor member 810 and the second conductor member 820 with a step, the steps are overlapped at the time of joining. Connection is possible without increasing the plate thickness.

  That is, the second conductor member 820 forms the convex portion 823 on the surface side where the FSW bonding trace remains in the portion where the connection portion with the first conductor member 810 is formed. On the other hand, the first conductor member 810 forms a concave portion connected to the convex portion 823 on the surface side where the FSW bonding trace remains in the portion where the connection portion with the second conductive member 820 is formed.

  As a result, the fluidity of the molding material 851 is improved and the occurrence of mold defects is suppressed compared to the case where the conductor members are connected without a step.

  Further, by making the end shape a stepped shape, the steps are overlapped at the time of joining and connected without increasing the bus bar plate thickness. Thereby, the height dimension at the time of a mold can be reduced and it leads to size reduction (low profile) of a product.

  FIG. 5 is a cross-sectional view regarding the joining configuration of the first conductor member 810 and the second conductor member 820 according to another embodiment.

  The first conductor member 810 made of copper is used as the lower surface, and the second conductor member 820 made of aluminum is placed on the upper surface of the first conductor member 810. Then, the FSW tool is brought into contact with the second conductor member 820. Thereby, copper can be softened with the heat which stirred the aluminum side, and a joint surface can be formed in the mating surface of the level difference directly under a tool.

  If the positions of copper and aluminum are reversed, or if copper and aluminum are abutted at the same time, the melting point on the copper side is higher than that of aluminum, so the aluminum melts and the soundness of the joint cannot be maintained. Because.

11 ... Substrate base, 20 ... Circuit board, 200 ... Power converter, 220 ... Housing, 300a ... Power semiconductor module, 300b ... Power semiconductor module, 300c ... Power semiconductor module, 302 ... Power module terminal, 500 ... Capacitor module, 701: Capacitor terminal, 801 ... First molded bus bar, 802 ... Second molded bus bar, 810 ... First conductor member, 811 ... First connection terminal, 812 ... Second connection terminal, 813 ... Third connection terminal, 814 ... First 1 connection part, 815 ... main body part, 816 ... concave part, 820 ... second conductor member, 821 ... capacitor side connection terminal, 822 ... second connection part, 823 ... convex part, 851 ... molding material, 852 ... molding material

Claims (2)

A plurality of power semiconductor modules;
A capacitor for smoothing DC power;
A conductor member connecting the plurality of power semiconductor modules and the capacitor;
The conductor member is
A first conductor member connected to the plurality of power semiconductor modules;
A second conductor member connected to the capacitor and made of a material different from the first conductor member and having lower conductivity than the first conductor member;
The first conductor member is
A main body forming a connection for connecting to the second conductor member;
A first connection terminal formed with a width smaller than the width of the main body and connected to any one DC terminal of the plurality of power semiconductor modules;
And a second connection terminal connected to a DC terminal of a power semiconductor module different from the power semiconductor module connected to the first connection terminal. . The power conversion device according to claim 1,
The second conductor member is formed with a convex portion on the surface side where the FSW bonding trace remains in the portion forming the connection portion with the first conductor member,
The first conductor member is a power conversion device in which a concave portion connected to the convex portion is formed on a surface side where an FSW joint trace remains in a portion forming a connection portion with the second conductive member.