JP2011115020A - Power unit - Google Patents

Abstract

Provided is a power unit that can be reduced in size while efficiently absorbing heat of a bus bar.
A power unit includes a power semiconductor element, an insulating substrate on which the power semiconductor element is mounted, and a bus bar that is electrically connected to the power semiconductor element. The bus bar 4 is configured by laminating a conductive member 9 and an insulating cooling member 10 each formed in a flat plate shape. A groove 13 is formed in the insulating cooling member 10 for circulating the refrigerant. The insulating cooling member 10 and the refrigerant absorb the heat of the bus bar 4 and cool the bus bar 4.
[Selection] Figure 1

Description

  The present invention relates to a power unit, and more particularly to a power unit used in a vehicle such as an electric vehicle or a hybrid vehicle.

  Conventionally, as described in JP 2009-135278 A as a power unit used in a vehicle, an insulating substrate on which a power semiconductor element is mounted, a bus bar electrically connected to the power semiconductor element by a bonding wire, What has a cooler which mounts an insulating substrate is known. Then, by integrally configuring the power semiconductor element and the cooler, heat from the power semiconductor element is efficiently transmitted to the cooler to cool the entire unit.

JP 2009-135278 A

  However, when increasing the output efficiency by applying a high DC voltage to the motor of the vehicle, the amount of heat generated by the power semiconductor element increases, the amount of heat transmitted from the bonding wire to the bus bar increases, and the temperature of the bus bar rises. It is difficult to cope with the cooling structure of the power unit. In order to suppress the temperature rise of the bus bar, a method of increasing the cross-sectional area of the bus bar can be considered. However, if the cross-sectional area of the bus bar is increased, there is a problem that it is difficult to reduce the size of the power unit.

  The present invention has been made to solve such a technical problem, and an object of the present invention is to provide a power unit that can be miniaturized while efficiently absorbing the heat of the bus bar.

  The power unit according to the present invention is a power unit having a power semiconductor element and a bus bar arranged around the power semiconductor element. The bus bar includes a conductive member electrically connected to the power semiconductor element, and insulation cooling that absorbs heat from the periphery. It is characterized by being laminated with a member.

  In the power unit according to the present invention, since the bus bar is formed by laminating the conductive member and the insulating cooling member, the heat transferred from the power semiconductor element and the heat generated by the bus bar are efficiently absorbed by the insulating cooling member. The semiconductor element and the bus bar are cooled. Accordingly, the bus bar can be thinned, and the power unit can be miniaturized.

  In the power unit according to the present invention, the bus bar is preferably formed by laminating a conductive member and an insulating cooling member in the thickness direction. In this way, the insulating cooling member can efficiently absorb and cool the heat of the bus bar. Moreover, it becomes easy to connect to the power semiconductor element.

  In the power unit according to the present invention, it is preferable that the insulating cooling member is provided with a refrigerant flow path for circulating the refrigerant. In this case, the heat of the bus bar can be further efficiently absorbed by using the refrigerant.

  In the power unit according to the present invention, it is preferable that the refrigerant forms a jet jet. In this way, the heat of the bus bar can be efficiently absorbed even in a narrow region between the bus bars.

  ADVANTAGE OF THE INVENTION According to this invention, the power unit which can achieve size reduction can be provided, absorbing the heat | fever of a bus bar efficiently.

It is sectional drawing of the power unit which concerns on 1st Embodiment. It is an electric circuit diagram showing a three-phase inverter. It is sectional drawing of the power unit which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a cross-sectional view of a power unit according to the first embodiment. As shown in FIG. 1, the power unit 1 includes a power semiconductor element 2, an insulating substrate 3 on which the power semiconductor element 2 is mounted, and a bus bar 4 that is electrically connected to the power semiconductor element 2. The power semiconductor element 2 and the insulating substrate 3 constitute a power semiconductor module. The power semiconductor element 2 is, for example, an IGBT (Insulated Gate Bipolar Transistor) element or a diode that constitutes an inverter circuit.

  FIG. 2 is an electric circuit diagram showing a three-phase inverter. As shown in FIG. 2, the inverter circuit is configured by a three-phase inverter bridge. That is, this inverter circuit is formed by connecting three sets of two IGBT elements Q11 and Q12 connected in series (bridge) in parallel, and the collector of the IGBT element Q11 is a DC power supply line P on the positive voltage side. And the emitter of IGBT element Q12 is connected to DC power supply line N on the negative voltage side. A connection point between the emitter of IGBT element Q11 and the collector of IGBT element Q12 is connected to a power input terminal of a motor (not shown). In addition, diodes D11 and D12 are connected in reverse direction in parallel with the IGBT elements Q11 and Q12.

  As shown in FIG. 1, the emitter 2 a located on the front side of the power semiconductor element 2 is connected to the bus bar 4 by bonding wires 6, and the collector 2 b located on the back side thereof is fixed to the insulating substrate 3 by the solder layer 5. Has been. The insulating substrate 3 is a DBA (Direct Brazed Aluminum) substrate, in which an upper metal layer 3a made of aluminum or an aluminum alloy, an aluminum nitride layer 3b that is an insulator, and a lower metal layer 3c made of aluminum or an aluminum alloy are laminated. It has the structure. The upper metal layer 3 a is electrically connected to the collector 2 b of the power semiconductor element 2 through the solder layer 5. The lower metal layer 3c is joined to the insulating cooler 8 by brazing.

  The insulating cooler 8 is formed in a substantially flat plate shape, and has an insulating substrate mounting portion 8 a for mounting the power semiconductor element 2 and the insulating substrate 3, and a bus bar mounting portion 8 b for mounting the bus bar 4. The insulating substrate 3 is fixed to the insulating substrate mounting portion 8a by brazing. The insulating cooler 8 is mainly composed of an insulating material such as ceramics.

  The bus bar 4 is configured by laminating a conductive member 9 and an insulating cooling member 10 each formed in a flat plate shape. As shown in FIG. 1, the bus bars 4 are alternately arranged with the flat conductive members 9 and the flat insulating cooling members 10 along the horizontal direction (thickness direction between the conductive members 9 and the insulating cooling members 10). Are stacked. Examples of the conductive member 9 include materials having high electrical conductivity such as aluminum and copper. The insulating cooling member 10 is formed of an insulating material such as ceramics as with the insulating cooler 8.

  The insulating cooling member 10 is formed integrally with the insulating cooler 8. That is, the insulating cooling member 10 is erected from the bus bar mounting portion 8b of the insulating cooler 8 and integrated with the bus bar mounting portion 8b. In this way, heat generated from the bus bar 4 is directly transferred to the insulating cooler 8 via the insulating cooling member 10. In addition, since the cross-sectional area of the bus bar 4 is determined by the fusing current, it increases as the heat generation temperature increases.

  A laminate formed by laminating the conductive member 9 and the insulating cooling member 10 is surrounded by a housing 11 disposed on the outer periphery thereof. The housing 11 is made of a resin material such as polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT).

  The P-pole bus bar 4 a of the bus bar 4 is electrically connected to the collector 2 b of the power semiconductor element 2 through the upper metal layer 3 a and the solder layer 5 of the insulating substrate 3 connected by the bonding wires 7. The N-pole bus bar 4 b is electrically connected to the emitter 2 a of the power semiconductor element 2 by a bonding wire 6. The P-pole bus bar 4a and the N-pole bus bar 4b are each composed of a conductive member 9, and are electrically insulated by an insulating cooling member 10 disposed therebetween.

  In the power unit 1 configured as described above, the amount of heat generated by the power semiconductor element 2 is transmitted to the insulating cooler 8 via the solder layer 5 and the insulating substrate 3. The insulation cooler 8 absorbs the heat transfer and cools the power semiconductor element 2 and the insulation substrate 3. A part of the heat generated by the power semiconductor element 2 is transmitted to the bus bar 4 via the bonding wires 6 and 7 and is efficiently absorbed by the insulating cooling member 10 together with the heat generated by the bus bar 4. As a result, the power semiconductor element 2 and the bus bar 4 are efficiently cooled by the insulating cooling member 10.

  In the power unit 1 according to the present embodiment, since the bus bar 4 is formed by laminating the conductive member 9 and the insulating cooling member 10, the amount of heat transferred from the power semiconductor element 2 and the amount of heat generated by the bus bar 4 are determined by the insulating cooling member 10. As a result, the power semiconductor element 2 and the bus bar 4 are cooled. Therefore, the bus bar 4 can be thinned, and the power unit 1 can be miniaturized.

  Further, since the bus bar 4 is formed by laminating the conductive member 9 and the insulating cooling member 10 in the thickness direction, the insulating cooling member 10 can efficiently absorb and cool the heat of the bus bar 4. For this reason, it becomes possible to cope with the high temperature of the element. That is, for example, when the power semiconductor element 2 is switched from a Si element (junction temperature 150 ° C.) to a SiC element (junction temperature 250 ° C.), the temperature of the bus bar 4 increases due to the amount of heat transferred to the bus bar 4 via the bonding wires 6. However, since the insulating cooling member 10 can efficiently absorb the heat transfer and cool the bus bar 4, the temperature rise of the bus bar 4 can be suppressed.

  Further, since the P-pole bus bar 4a and the N-pole bus bar 4b are electrically insulated by the insulating cooling member 10 disposed therebetween, the insulation distance can be shortened compared to the conventional case. Moreover, it becomes easy to connect to the power semiconductor element. Further, by arranging the bus bars 4 in the vertical direction as shown in FIG. 1, it is possible to reduce the thickness in the plane direction.

  Further, conventionally, when the heat-resistant temperature of the housing resin (for example, PPS) exceeds 200 ° C., it is necessary to cool the housing resin by using an insulating cooler arranged on the lower surface thereof. Then, since the heat can be absorbed not only by the insulating cooler 8 disposed on the lower surface of the housing 11 but also by the insulating cooling member 10, the housing 11 can be efficiently cooled.

  Further, the bonding life of the wiring including the bonding wires 6 and 7 is caused by the power cycle of the power semiconductor element 2. In the power unit 1 according to the present embodiment, since the insulating cooling member 10 efficiently absorbs the heat of the power semiconductor element 2 and the bus bar 4, the temperature rise of the wiring and the bus bar 4 can be suppressed, and the bonding life can be extended. It becomes possible. Moreover, generation | occurrence | production of peeling of the resin interface of the housing 11 can be prevented by suppressing the temperature rise of the bus bar 4. As a result, the reliability of the power unit 1 can be increased.

(Second Embodiment)
FIG. 3 is a cross-sectional view of a power unit according to the second embodiment. The difference between the power unit 12 according to the second embodiment and the first embodiment is that a refrigerant flow path is provided for circulating the refrigerant through the insulating cooling member 10 and the insulating cooler 8 of the bus bar 4. Since the other configuration of the power unit 12 according to the present embodiment is the same as that of the power unit 1 according to the first embodiment, the same reference numerals are given and redundant description is omitted.

  As shown in FIG. 3, each insulating cooling member 10 is formed with a groove 13 for circulating a refrigerant. These grooves 13 are formed at locations close to the joint such as W / B (wire bond) or T / B (tape bond) so as to open downward. Further, in the insulating substrate mounting portion 8a of the insulating cooler 8, a plurality of grooves 14 for circulating the coolant are formed in a region corresponding to the place where the insulating substrate 3 is mounted. These grooves 14 are open downward. The refrigerant flows into the grooves 13 and 14 and absorbs heat from the insulating cooler 8 and the insulating cooling member 10. The refrigerant preferably forms a jet jet.

  With such a configuration, the power unit 12 can obtain the same effect as that of the power unit 1 according to the first embodiment. In addition, the bus bar 4 can be further formed using the refrigerant by providing the insulating cooling member 10 with the groove 13 for circulating the refrigerant. Can be efficiently absorbed. In addition, since the refrigerant forms a jet jet, the heat of the bus bar 4 can be efficiently absorbed even in a narrow region between the P-pole bus bar 4a and the N-pole bus bar 4b.

  The power unit according to the present invention is not limited to that described in the above embodiment. The power unit according to the present invention may be obtained by modifying the power unit according to the embodiment so as not to change the gist described in each claim or applying the power unit to another. For example, in the above embodiment, wire bonding is used as a wiring bonding method, but tape bonding or direct lead bonding may be used. In addition to the groove, a channel such as a hole may be provided as the coolant channel for circulating the coolant.

DESCRIPTION OF SYMBOLS 1,12 ... Power unit, 2 ... Power semiconductor element, 4 ... Bus bar, 4a ... P pole bus bar, 4b ... N pole bus bar, 9 ... Conductive member, 10 ... Insulation cooling member, 11 ... Housing, Q11, Q12 ... IGBT element, D11, D12 ... diode, 13, 14 ... groove.

Claims (4)

In a power unit having a power semiconductor element and a bus bar arranged around the power semiconductor element,
The bus bar is formed by laminating a conductive member electrically connected to the power semiconductor element and an insulating cooling member that absorbs heat from the surroundings.   The power unit according to claim 1, wherein the bus bar is formed by laminating the conductive member and the insulating cooling member in a thickness direction thereof.   The power unit according to claim 2, wherein the insulating cooling member is provided with a refrigerant flow path for circulating the refrigerant.   The power unit according to claim 3, wherein the refrigerant forms a jet jet.

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