WO2017140579A1

WO2017140579A1 - Vertical structure of a half-bridge

Info

Publication number: WO2017140579A1
Application number: PCT/EP2017/052947
Authority: WO
Inventors: Manuel Blum; Marek Galek; Monika POEBL; Martin Schulz
Original assignee: Siemens Aktiengesellschaft
Priority date: 2016-02-18
Filing date: 2017-02-10
Publication date: 2017-08-24
Also published as: DE102016202509A1

Abstract

A converter with high switching speed and improved heat dissipation is to be provided. To this end, the invention relates to a converter with a half-bridge comprising a first and a second switching element (S1, S2) and a first heat-conducting plate (3) as a carrier for the first switching element (S1). The converter also comprises a second heat-conducting plate (4) as a carrier for the second switching element (S2). The first heat-conducting plate (3) with first contacts (10, 11) for the first switching element (S1) is symmetrically arranged, relative to a plane of symmetry, in relation to the second heat-conducting plate (4) with second contacts (12, 13) for the second switching element (S2). The first heat-conducting plate (3) and the second heat-conducting plate (4) are both arranged parallel to the plane of symmetry.

Description

description

A vertical structure of a half-bridge The present invention relates to a power converter with egg ^¬ ner half-bridge, having a first and a second switching element, and having a heat conducting plate as a carrier of the first switching element. Power converters are used to convert an injected current into an output current in which a parameter such as the voltage or the frequency is changed. Accordingly, under failed ^¬ det to different types of converters with which alternating current is directed into direct current, eg rectifiers, inverters, with which direct current is directed into alternating current and inverter with which an alternating current is directed to another AC with a different frequency. All of these types of power converters are affected by the present invention. Also with respect of the scope the present invention is not limited to a clamping ^¬ voltage range. Thus, both low voltage applications as well as medium and high voltage applications are conceivable. Also with regard to the technology of the power semiconductors, there are no restrictions here.

Power converters are usually constructed with one or more half-bridges. Such a half-bridge is coupled, for example, to a DC voltage intermediate circuit. This can be a high-side switch as a first switching element and a low-side switch as a second switching element processin ^¬ ren. The high-side switch and the low-side switches are typically on and off alternately in the operation of the converter , Since the leads to the switches or circuit breakers form inductors, when switching the switch voltage spikes, which can lead to losses, disturbances or damage. The inductances relevant for switching or commutating are called Commutation Inductivities respectively

Circular inducements.

When constructing switching cells or switching bridges, it is therefore essential to obtain a low commutation inductance. At the same time should be an efficient

Heat dissipation of the lossy components (circuit breakers) are guaranteed. These two points are difficult to reconcile with herkömm ^¬ Licher construction technique. For a good heat dissipation large areas are needed for heat spreading. However, these ensure increased circular inductance.

Due to the conventional, planar construction of the half-bridges, in order to minimize the influence of circulating inductors, the switching speeds used to be kept low in order to keep the voltage peaks low. Low switching speeds lead to further losses. An optimized structure with regard to the circular inductance usually led to an ineffective cooling, which was then often accepted.

The object of the present invention is therefore to provide a power converter in which both high

Switching speeds are possible as well as an improved heat dissipation.

According to the invention this object is achieved by a current ^¬ judge with

a half-bridge having a first and a second switching element, and

- A first heat conduction plate as a carrier of the first

Switching element, as well as with

- A second heat conduction plate as a carrier of the second switching element, wherein

- the first heat conducting plate to a symmetry plane ^¬ to the second heat conduction plate is arranged at a second Kon ^¬ clock for the second switching element to the first contacts for the first switching element and symmetrically with respect to - The first heat conduction plate and the second Wärmelei ^¬ tion plate are each parallel to the plane of symmetry.

In an advantageous manner, therefore, a second heat conduction plate for the second is next to the first Wärmelei- tion plate

Switching element of the half-bridge provided. Thus, the heat ^{removal ¬ is} practically doubled. This is in particular also because ^¬ ran, that the heat conduction plates are ge ^¬ forms as separate components. With regard to a reduced circular inductance or commutation inductance, in contrast to a purely planar structure, a three-dimensional structure is provided. This means that the individual components are not only arranged next to each other, but also over ^¬ nander. Specifically, the two heat conduction plates are parallel to each other and symmetrical to a plane of symmetry angeord ^¬ net, to which they are also arranged in parallel. Not only the two heat conduction plates themselves, but also the principal locations of the respective switching elements located thereon can thus be arranged symmetrically with respect to one another with respect to the plane of symmetry. By this symmetry in the vertical direction, ie perpendicular to the plane of symmetry, will be apparent to the leads simplified conditions especially with regard to their geometry for A possible ^¬ lichst low inductance. The vertical construction of the half-bridge or Kommutierungszelle thus both goals can be achieved together, namely a verbes ^¬ serte heat dissipation using the minimum inductance for high switching speeds. Preferably, a first load output contact of the first

Switching element with a second load output contact of the two ^¬ th switching element directly electrically connected. This results in not only a simple electrical or mechanical structure, but also an extremely short connection distance of the two load output contacts, which is again ^¬ rum advantageous in terms of minimum inductance. In one embodiment, a positive pole of the first switching element is separated from a negative pole of the second switching element only by an insulating film. The positive pole and the negative pole thus represent electrically separate contacts that can be contacted with the high side or the low side of the intermediate circuit. The vertically above one another in the direction perpendicular to the plane of symmetry structure of the two contacts (Mi ^¬ nuspol and positive pole) also results in a reduced circuit inductance.

In a specific embodiment, a four-layer structure of the half-bridge may be selected. In a first layer is the first heat conduction plate and in a second

Layer of the first load output contact, the first switching element and the positive pole each side by side in a second plane parallel to the plane of symmetry. In a third layer befin ^¬ det the second load output contact, the second shawl Tele ^¬ ment and its negative pole, adjacent to each other in a drit ^¬ th plane parallel to the plane of symmetry. The second heat transfer plate is finally in a fourth

Layer. The four layers are preferably located in a direction perpendicular to the plane of symmetry flush immediacy ^¬ bar above the other. It is particularly advantageous if the construction height of the second and third layer is determined by the respective contacts (first load output contact and positive pole in the second layer or second load output contact and negative pole in the third layer). The two switching elements should be designed structurally less high than the individual contacts, so that the switching elements do not touch, and the contacts are used practically as a spacer for the heat conduction plates but also for the switching elements. Since the switching elements are preferably located in the middle between the respective contacts and the contacts are higher than the switching elements, results between the switching elements, a distance or a space.

In an advantageous embodiment, the first switching element and the second switching element have in one direction perpendicular to the plane of symmetry a predetermined distance. This distance can be specified in terms of the required insulation or to be incurred Potentialun ^¬ terschied. This predetermined distance can be easily adjusted by the height of the contacts of the switching elements.

The space between the first and second switching element may be filled with a molding compound. This molding compound is preferably an insulating plastic. It not only increases the insulation resistance of the half-bridge, but also ensures protection of the switching elements against environmental influences. In a further embodiment of the power converter, the two heat conduction plates are IMS plates

(Insulated Metallic Substrates). Such standard plates not only provide for the necessary electrical insulation of components mounted thereon, but also for their efficient heat dissipation.

According to a further embodiment, the two load output contacts and the positive pole and the negative pole are each ^¬ Weil designed as copper bars, which are each mounted directly on the respective heat conduction plate. The contacts as copper bars thus have the multiple Funktionali ^¬ ity as spacers, as a good electrical conductor and as a good thermal conductor. The two switching elements of the half-bridge may be IGBTs. Alternatively, however, any other semiconductor switching elements can be used. It is advantageous, however, if the performance path of the respective

Linearly extending switching element, so that can be easily realized with the symmetrical second switching element optimization with respect to the inductance. The half bridge can be connected to a busbar via a busbar

Capacitor bank be connected. Due to the symmetry of the half bridge, the geometry of the shift rail can also be kept simple.

The following invention will now be described in detail with reference to the accompanying drawings, in which:

1 shows a schematic circuit diagram of a power converter with a half-bridge;

2 shows a voltage curve at the output of the power converter of FIG. 1;

3 shows the course of a switching signal for one of

Switching elements of the power converter; and

4 shows the three-dimensional structure of a half-bridge according to the present invention.

The embodiments described in more detail below represent preferred embodiments of the present invention. It should be noted that the individual features can be realized not only in the described feature combinations, but also in isolation or in other technically meaningful combinations.

A power converter has, by way of example, the schematic structure of FIG. 1. The centerpiece is a half-bridge having a first switching element S1 and a second switching element S2. The the switching elements Sl and S2 are each bridged in ^¬ by a free-wheeling diode Dl or D2 ^¬. The switch Sl is connected to a center tap M via a line with a line inductance LI. Similarly, the second switching element S2 is connected by a line having the lead inductance L2, is joined to the center tap ^¬ M. To the half-bridge, for example, a DC ^{link is ¬} closed, which is symbolized here by a capacitor C. Specifically, this capacitor C is connected to the two contacts of the respective switching elements Sl and S2, which are remote from the center tap M.

From the center tap M leads a line with a line inductance L3 to the output of the power converter. About the ^¬ se lead inductance L3, a current flows I. As a voltage to a possible load on the output results in the voltage value U _L.

The voltage curve at the output of the converter is in

2 shows an example. In the underlying FIG 3, a corresponding switching signal U _{s is} shown. One of the switching elements Sl is to be a time turned rela ^¬ hung as S2 and the other off. The conduction inductances LI to L3 result in a commutation voltage peak 1. This is, for example, above a limit value U _g and is therefore not tolerable.

To solve this problem and also for improved heat dissipation of the switching elements Sl and S2, a three-dimensional construction technique for a half-bridge of the converter is proposed differently from the conventional, planar construction technique. An example of this is shown in FIG. 4 in a perspective view. The exemplary half-bridge shown in FIG. 4 has a plane of symmetry (which is not shown in the FIG) to which a first heat conduction plate 3 and a second heat conduction plate 4 extend in parallel. The two heat ^¬ line plates 3 and 4 are carriers of the switching elements Sl and S2. The two switching elements Sl and S2 are arranged in the example of FIG 4 on the mutually facing sides of the heat conduction plates 3 and 4. In this respect the prinzipiel ^¬ le place of switching elements is symmetrical to the symmetry level, but the actual arrangement and orientation of the switching elements Sl and S2 need not be symmetrical to one another in relation to one another. Optionally, it is point symmetric.

The circuit elements Sl and S2 may be formed as IGBTs, as is sketchily indicated in FIG 4. Accordingly, the switching element Sl has drain 5 and source 6. In addition, 4 bonding wires 8 between drain 5 and source 6 are indicated in FIG. Of the second switching element S2, bonding wires 9 can be seen in FIG.

Switching element Sl is for example a high-side switch is. Source 6 a last output contact is therefore associated with 10 and drain 5, a plus pole 11. Analogously, is the drain of the second switching element S2, a load leaving ^¬ contact 12 and the source of the second switching element S2, a Minuspolkontakt 13 assigned. The contacts 10, 11, 12 and 13 may be formed as copper platelets. In addition, may be equal in size each un ^¬ behind the other. Their thickness in the direction perpendicular to the plane of symmetry determines the distance between the two Wärmelei ^¬ tion plates 3 and 4. The two load output contacts 10 and 12 are mounted directly to each other, for example screwed together and outside the Wärmelei ^¬ tion plates 3 and 4 are added immediately. Optionally, the two load output contacts 10 and 12 are formed as a one-piece Kontaktele ^¬ ment.

The plus-pole contact 11 and the minus-pole contact 13 are electrically separated from one another by an insulation layer or insulation film lying in the plane of symmetry. The positive pole contact 11 is applied directly to the heat conduction ^¬ plate 3 and the negative terminal 13 directly on the heat conduction plate. 4

A first contact block, consisting of the two load output contacts 10 and 12 and a second contact block, best From the plus pole contact 11, the negative pole contact 13 and the insulation 14 therebetween, have a lateral distance to the first contact block, by which a space 15 is defined, which is also delimited by the heat conduction plates 3 and 4. In this example, cuboid space, the switching elements Sl and S2 are. The height of this space 15 can be determined for example by a minimum distance of the bonding wires 8 and 9 for a given geometry of the bonding wires. Such a minimum distance may be due to a predefined dielectric strength. The distance between the switching elements Sl and S2 or their bonding wires 8 and 9 can be adjusted, for example, simply by the height of the copper platelets used for the contacts 10 to 13. The thickness of the insulating film 14 plays virtually no role.

The space 15 may be formed by a so-called "molding compound" ausgegos ^¬ sen. It is preferably a synthetic ^¬ material that has a comparison increased air Durchschlagtes- ACTION so that the molding compound protects the scarf Tele ^¬ elements Sl and S2 not only. from environmental influences, but also in increased mass before punches the sake of clarity. the molding compound in FIG 4 but not shown. in a concrete example, so exemplary results for Halbbrü ^¬ bridge of the power converter that shown in FIG 4 4-layer construction, The layers are each parallel to the plane of symmetry and are arranged directly above one another in the following order: The first layer forms the first heat conduction plate 3. It forms the support for the second layer, which is the first load output contact 10 and the positive pole contact 11 with interposed first switching element Sl is formed The height of this second

Layer is determined by the two contacts 10 and 11. The first switching element Sl should be slightly lower. Un ^¬ indirectly on the second layer is the third layer consisting of the second load output contact 12 and the negative pole contact 13 (the insulating layer 14 is ignored here because of their small layer thickness) with interposed second switching element S2. Above the third layer is immediately the fourth layer, which is formed by the second heat conduction plate 4 as a carrier of the third layer. In this case, the third and the fourth layer are symmetrical with respect to the first and second layer, if appropriate only with the exception of the orientation of the switching elements S1 and S2.

By using the third dimension, i. the vertically superimposed switching elements or Kom mutationspartner the half-bridge, both the heat dissipation and the size of the circular inductance can be optimized, because it can be used an additional heat conduction plate and the geometry of the lines to the switching elements can be better designed in view of the resulting inductance become. Thus, during commutation, reduced voltage spikes 2 according to FIG. Second

For high current applications, large conductor cross sections are required for the contacts 10 to 13. In this case geeig ^¬ items copper bars can be used which are preferably up brought to IMS circuit boards that form the heat conduction plates or soldered.

The plus pole contact 11 and the Minuspolkontakt 13 with Between the seats ^¬ rule lying insulation 14 can be realized as a busbar, to the low inductance capacitor bank a reasonable can be concluded. So a 4x5 matrix of capacitors as an intermediate circuit capacity to the Halbbrü ^¬ bridge example, can be connected.

The heat conduction plate used for heat dissipation for each switching element can be customized for the switching element opti ^¬ mized. In this case, the symmetry refers only to the basic arrangement of the switching elements and Heat conduction plates, but not on the exact geometry of the heat conduction plates with each other.

Claims

claims

1. Power converter with

- A half-bridge having a first and a second switching element (Sl, S2), and

a first heat conduction plate (3) as a carrier of the first switching element (S2),

marked by

- A second heat conduction plate (4) as a carrier of the second switching element (S2), wherein

- The first heat conduction plate (3) with first contacts

(10, 11) for the first switching element (Sl) is arranged symmetrically be ^¬ delay a symmetry plane to the second heat conduction ^¬ plate (4) with second contacts (12, 13) for the second switching element (S2) and

- The first heat conduction plate (3) and the second Wärmelei ^¬ tion plate (4) are each parallel to the plane of symmetry.

Second power converter according to claim 1, wherein a first load output contact (10) for the first switching element (Sl) with a second load output contact (12) for the second switching element (S2) is electrically connected directly.

3. A power converter according to claim 1 or 2, wherein a positive pole contact (11) for the first switching element (Sl) only by an insulating film (14) of a negative terminal contact (13) for the second switching element (S2) is separated.

4. A power converter according to all of the preceding claims, wherein the half-bridge has the following layer structure:

first layer: first heat conduction plate (3),

second layer: first load output contact (10), first

Switching element (Sl) and positive pole contact (11), each adjacent to each other substantially in a second plane parallel to the plane of symmetry,

third layer: second load output contact (12), second switching element (S2) and negative pole contact (13), in each case essentially in a third plane parallel to the plane of symmetry and

fourth layer: second heat conduction plate (4).

5. Converter according to one of the preceding claims, wherein the first switching element (Sl) and the second switching element (S2) in a direction perpendicular to the plane of symmetry have a predetermined distance.

6. Converter according to one of the preceding claims, wherein a space between the first and the second switching element (Sl, S2) is filled with a molding compound.

7. A power converter according to one of the preceding claims, wherein the two heat conduction plates (3, 4) are IMS

Plates is.

8. Converter according to one of the preceding claims with reference to claim 2 and 3, wherein the two Lastabgangs- contacts (10,12), the positive pole contact (11) and the negative pole ^¬ contact (13) are each formed as copper bars, each directly are mounted on the respective heat conduction plate (3,4).

9. Converter according to one of the preceding claims, wherein it is IGBTs in the two switching elements (Sl, S2).

10. Power converter according to one of the preceding claims, wherein the half-bridge via a busbar to a

Capacitor bank is connected.