EP3127408A1

EP3127408A1 - Driver assembly

Info

Publication number: EP3127408A1
Application number: EP15707572.2A
Authority: EP
Inventors: Jorg Jahn; Thomas Erdmann; Ajoy Palit
Original assignee: Lemfoerder Electronic GmbH
Current assignee: Lemfoerder Electronic GmbH
Priority date: 2014-03-31
Filing date: 2015-02-19
Publication date: 2017-02-08
Also published as: DE102014205956A1; CN106416446A; JP6506771B2; US9917533B2; US20170110984A1; JP2017518628A; CN106416446B; WO2015149987A1; KR20160138212A

Abstract

The invention relates to a driver assembly (100) comprising a plurality of semiconductor switches (105) which are arranged in a plane (110) such that distances between adjacent semiconductor switches in the plane are each equally large and each semiconductor switch has the same number of adjacent semiconductor switches.

Description

Treiberbauqruppe

The invention relates to a driver assembly. In particular, the invention relates to the dissipation of heat from elements of the driver assembly.

A control device, for example, onboard a motor vehicle, is configured to provide a current or voltage to control a connected load. For example, a three-phase AC voltage may be provided to control the direction of rotation and rotational speed of a connected electric motor.

A driver assembly includes a plurality of semiconductor switches to provide the required current or voltage. The semiconductor switches are usually not lossless, so heat must be dissipated by them. To lead leads to the semiconductor switches as short as possible and direct and to be able to cool by means of a common heat sink, the semiconductor switches are usually arranged in a row or in a matrix form. In this case, semiconductor switches, which are located in outer regions of the arrangement, cooled better than further inside semiconductor switch. Due to the different temperatures, the semiconductor switches can be electrically loaded differently, so that the total electrical load of the driver assembly can be reduced. The semiconductor switches can also age different degrees or fast, so that their failure probabilities are different. The probability of failure of the entire driver module can thereby be increased. In addition, supply lines to the semiconductor switches can be of different lengths, which may adversely affect electromagnetic compatibility (EMC), impedance or voltage drop in the supply line.

It is an object of the present invention to provide an improved driver assembly. The invention solves this problem by means of a driver assembly with the features of the independent claim. Subclaims give preferred embodiments again. A driver assembly according to the invention comprises a plurality of semiconductor switches, which are arranged in a plane such that distances between adjacent semiconductor switches in the plane are equal in size and each semiconductor switch has the same number of adjacent semiconductor switches.

The semiconductor switches may comprise, for example, bipolar transistors, field-effect transistors, MOSFETs, thyristors, switching diodes or IGBTs. The semiconductor switches are preferably discrete components that can be individually positioned in the plane. If each semiconductor switch emits the same thermal power, the same temperatures can be set on the semiconductor switches. A thermal energy input at the location of a semiconductor switch, due to adjacent semiconductor switches is due to their arrangement for all semiconductor switches the same size. The same temperatures can mean equal aging, equal loadings or equal failure probabilities for the semiconductor switches. The driver assembly can thereby be more reliable or resilient.

In a preferred embodiment, the semiconductor switches are evenly distributed on a circular line. In other words, the arrangement of the semiconductor switches in the plane may be rotationally symmetric about a predetermined point. It is further preferred that this is an n-fold rotational symmetry, where n is the number of semiconductor switches used.

In one embodiment, spacings between the semiconductor switches are defined as the smallest distances from points of their outlines in the plane. In another embodiment, a dot may be distinguished on each semiconductor switch, the distance between two semiconductor switches being defined as the distance between the associated dots. The excellent point may be, for example, a geometric center or a point that is most heated during operation of the semiconductor switch. The position of a semiconductor switch may be indicated by the position of the designated point.

In one embodiment, it suffices if the distinguished points have the described relative distances, with rotational orientations of the Semiconductor switch in the plane can be freely selected. As a result, electrical supply lines to the semiconductor switches can advantageously be made short or with little crossing.

In another embodiment, the rotational orientations of the semiconductor switches to each other or with respect to a reference point of importance. The semiconductor switches can in particular be aligned uniformly with respect to each other. For this purpose, a direction can be predetermined at each semiconductor switch, which preferably runs through the above-mentioned excellent point. For example, the directions of the semiconductor switches may be parallel to each other or angles including the directions with a common point may be the same for all semiconductor switches. Thus, a uniform heat distribution within the driver assembly can be improved in particular if the semiconductor switches can not be modeled with sufficient accuracy as radially symmetric heat sources.

It is further preferred that at least six semiconductor switches are provided, wherein the driver assembly is at least comprised of a multi-phase inverter. Such an inverter usually comprises a plurality of half bridges, each with two semiconductor switches. The polyphase inverter may be arranged in particular for controlling a polyphase electric motor. The inverter may in particular be provided on board a motor vehicle, for example for a steering or brake assistance, an electric rear axle steering, an electrical height adjustment (leveling-by-wire) and for electric drives. Furthermore, the inverter can be provided for two-wheelers, which usually have little space.

Preferably, at least one of the half bridges is electrically coupled to a further semiconductor switch as a phase separator, through which the corresponding formed by the half-bridge phase can be separated. As a result, a safe state can be generated in the event of a fault. More preferably, each of the half-bridges is electrically coupled to a further semiconductor switch as a phase separator. Further preferred is the phase separator of the associated half-bridge in an electrical Provided downstream line. Such a phase separation can be provided in particular for an emergency running strategy, for example of an electrical steering or other type of support.

It is further preferred that the at least one phase separator is arranged in a plane parallel to the semiconductor switches. For example, the at least one phase separator may be arranged on a different side of a semiconductor switch carrier element than the semiconductor switches. The carrier element is preferably a circuit board. It is further preferred that, if more than one phase separator is provided, the phase separators are arranged on the other side in a manner as described for the semiconductor switches. Alternatively, the phase separators may be arranged together with the semiconductor switches in a plane in a prescribed manner. Thus, each can achieve the same advantages described above for the phase separator.

It is further preferred that the phase separators and the semiconductor switches are arranged in different planes each on a circular line, wherein the circular line associated with the phase separator is surrounded in a plane passing through the plan view of the semiconductor switches associated circular line. As a result, a thermal load of a carrier material of the semiconductor switch and the phase separator exhibiting carrier element can be equalized. Furthermore, a possible temperature input to the semiconductor switches can be reduced. Furthermore, a compact arrangement of the semiconductor switches and the phase separator is possible. More preferably, the circular lines have a common center axis passing through the planes. This allows a more uniform thermal load of the carrier material can be achieved.

Preferably, a heat sink for thermal coupling to the semiconductor switches and further preferably provided with the at least one phase separator, wherein the heat sink comprises a plurality of lying in a plane contact portions for contact with the semiconductor switches and more preferably on the at least one phase separator. By using a single heat sink, the semiconductor switches and more preferably the at least one phase separator be cooled evenly and there may be cost advantages for material and assembly.

In one embodiment, the contact portions are encompassed by a contact surface, which has the shape of a circular disk. A surface of the heat sink facing the semiconductor switches, and more preferably the at least one phase separator, can thereby be formed in a simple and cost-saving manner. In another embodiment, the contact portions are encompassed by a contact surface which has the shape of a regular polygon with as many corners as semiconductor switches and more preferably arranged in the same plane phase separator abut the heat sink. A cooling capacity of the heat sink can be improved. In addition, the attachment of the heat sink may be facilitated by its polygonal (polygonal) shape. The heat sink may further preferably be formed by a housing of a synchronous motor or alternatively flanged to the housing. The latter is particularly advantageous for a frontal mounting of the inverter along with high tightness requirements.

The rotary arrangement of the semiconductor switch or the phase separator is also particularly advantageous for a direct connection of the inverter to a front side or contact side of a synchronous motor. As a result, contacting can take place by the shortest path by connecting the motor contacts to the carrier element or to carrier element contacts. For this purpose, the central free space of the semiconductor device can be advantageously utilized. Further preferably, a motor shaft end with integrated magnet can be passed through the free space by means of a hole cutout to a rotor position sensor, which is for example a Hall sensor and further preferably is arranged on a parallel to the support member further support member or board, a rotation angle to detect.

In one embodiment, the semiconductor switches, and more preferably the at least one phase separator comprise surface mounted devices, wherein the semiconductor switches, and more preferably the at least one phase separator, are electrically contacted by conductive traces and the heat sink is external to the plane lying projection for thermal coupling with at least one conductor track summarizes. As a result, the printed conductor can additionally be cooled, so that a "not spot" in the area of the driver assembly can be avoided in an improved manner The semiconductor switches and more preferably the at least one phase separator can be arranged in any surface-mountable housings, wherein in a particularly preferred embodiment Embodiment DirectFETs are used.

According to a preferred embodiment, each half-bridge is associated with a short-circuiting switch, which is electrically coupled to a line path which electrically interconnects the two semiconductor switches of the half-bridge, the short-circuiting switches being electrically connected to one another. By means of the short circuit switch, for example, an electric motor for use as a generator can be braked. Alternatively or additionally, deceleration up to a standstill of an electric motor can be the result of a safety requirement which, in the event of a fault, requires a severe or blocking motor system, which preferably corresponds to a safe state. For example, such a safety requirement or such a phase short circuit can be advantageously used for active rear wheel steering systems.

Preferably, the shorting switch is a MOSFET or a DirectFET. More preferably, the short-circuiting switches are arranged in a manner described above relating to the semiconductor switches or phase separators, and more preferably coupled to a heat sink. This arrangement and coupling is particularly recommended if the short-circuiting switches are to be cooled. Otherwise, as described above arrangement of the short circuit switch, which are preferably arranged in a different plane than the semiconductor switches, not mandatory.

Furthermore, it is preferred that conductor tracks for the electrical connection of terminals of the semiconductor switches have substantially equal surfaces. Due to the specified arrangement of the semiconductor switches in the plane, it is possible to design the electrical connections geometrically similar. In particular, it is preferred that the interconnects to the different semiconductor switches are substantially the same length, the same width and the same thickness. Electrical characteristics ka such as an electrical resistance, an impedance or an effect on electromagnetic interference fields can correspond to each other. Furthermore, the currents of the individual phases can be adapted to each other. Furthermore, the lowest possible EMC emission can be achieved. If the semiconductor switches are electrically charged uniformly, thermal powers in the region of the printed conductors can also correspond to one another. These preferred embodiments of printed conductors are preferably applicable to printed conductors for electrically connecting terminals of the phase separator (s) and / or the short-circuiting switches.

In a variant, the driver assembly comprises a predetermined number of semiconductor switches, each semiconductor switch being associated with one of at least two of the driver assemblies described above. In other words, the semiconductor switches of the driver assembly can also be arranged in two or more groups, wherein the described AnOrdnungsvorschriften apply to each group. The two groups can be arranged in one plane or in different planes. In one embodiment, the levels of the groups are parallel to each other.

Further preferably, a redundant inverter circuit with phase separator or short-circuit switch can be provided according to one of the above-described embodiments.

The invention will now be described in more detail with reference to the attached figures, in which:

FIG. 1 shows an arrangement of semiconductor switches of a driver assembly;

FIG. 2 shows an alternative arrangement of the semiconductor switches of FIG. 1;

Figure 3 is a circuit diagram of a three-phase inverter in the arrangement of Figure 1;

Figure 4 is a circuit diagram of a three-phase inverter shown in the arrangement of Figure 1 with phase separator in the arrangement of Figure 1, and Figure 5 is a circuit diagram of a three-phase inverter shown in the arrangement of Figure 1 with shorting switch

FIG. 6 is a side view of an embodiment of the driver assembly of FIG

1, and

FIG. 7 shows a representation of temperatures at the three-phase inverter of FIG. 3

represents.

FIG. 1 shows a schematic representation of a driver module 100. The driver module 100 comprises a number of semiconductor switches 105, wherein in FIG. 1, purely by way of example, six semiconductor switches 105 are provided. The semiconductor switches 105 are of the same type and arranged in a plane 1 10 two-dimensional. In this case, the arrangement is such that each semiconductor switch 105 has the same number of adjacent semiconductor switches 105 and distances between adjacent semiconductor switches 105 are the same in each case.

In the illustrated embodiment, the semiconductor switches 105 are equally distributed on a circular line 1 15 about a center 120. The semiconductor switch 105 are thus offset on the circular line 1 15 by 60 ° to each other. This arrangement has a 6-fold rotational symmetry with respect to the center point 120.

The arrangement of the semiconductor switch 105 is selected so that a common heat sink 125 for thermal coupling to the semiconductor switches 105 may have a contact surface 130 which is rotationally symmetric to the center 120 and parallel to the plane 1 10. In the illustrated embodiment, the contact surface 130 of the heat sink 125 has the shape of a circular disk; In another embodiment, the contact surface 130 may also have the shape of a regular polygon, wherein it is preferred that the number of corners corresponds to the number of applied semiconductor switches 105.

The arrangement of the semiconductor switch 105 is selected mainly for thermal reasons. Small errors or tolerances in the arrangement of the semiconductor switches 105 can therefore be generally accepted. Is an increased precision of Orientation is required, so at each semiconductor switch 105, a point 135 be distinguished, with respect to which the positions or distances between the semiconductor switches 105 are sized. In the embodiment shown, each of the designated locations corresponds to a geometric center of the surface of the semiconductor switches, and the designated locations 135 are respectively on the circle 15, where distances between the locations 135 of adjacent semiconductor switches 105 adjacent to each other are equal , In a further embodiment, the spacings of the semiconductor switches 105 are defined with respect to each other with respect to smallest distances of their outlines in the plane. In the illustrated embodiment, rotational orientations of the semiconductor switches 105 to each other in the plane 1 10 are selected differently.

In another embodiment, the rotational orientation of each semiconductor switch 105 with respect to the center 120 is also taken into account. This may be useful, for example, if outlines of the semiconductor switch 105 in the plane 1 10 are different from those shown in Figure 1 elongated. For determining the orientation, a direction 140 may be predetermined on the semiconductor switch 105, which direction preferably extends from the designated position 135. In order to align the orientations of the semiconductor switches 105 with each other with respect to the center 120, it is preferable to choose angles congruent with the directions 140 having radii through the center 120, respectively. In another embodiment, the directions 140 may be aligned with each other in other ways, such as by the directions 140 being parallel or in pairs perpendicular to each other.

In the illustration of Figure 1, each semiconductor switch 105 has exactly two adjacent semiconductor switch 105, namely a right and a left on the circle 1 15. Further away semiconductor switch 105, between which on the circle line 15 1 another semiconductor switch 105, are considered not adjacent.

In one embodiment, distances between non-contiguous semiconductor switches are at least 1.5 times the spacing between adjacent semiconductor switches 105. This condition can be used to ensure that the influence of heat of a semiconductor switch 105 on a non-adjacent semiconductor switch 105. conductor switch 105 is negligibly small. In the illustrated embodiment of six semiconductor switches 105 on the circle line 15, non-adjacent semiconductor switches 105 are, for example, at least 1.7 times as far apart from each other as adjacent semiconductor switches 105.

FIG. 2 shows an alternative arrangement of the semiconductor switches 105 of the driver assembly 100 of FIG. Here, a first group 205 and a second group 210 are formed, each comprising a plurality of semiconductor switches 105 of the driver assembly 100. By way of example, three semiconductor switches 105 are present in each group 205, 210. In each group 205, 210, the semiconductor switches 105 are arranged according to the specifications which were explained above with reference to the arrangement of FIG. In the illustrated embodiment, each group 205, 210 is associated with a separate heat sink 125; In an alternative embodiment, a single heat sink 125 may be used if all the semiconductor switches 105 are in the same plane 110. In yet another embodiment, the semiconductor switches 105 may also be in parallel planes 110, with the heat sinks 125 each extending in the direction away from the other plane 110. In particular, the semiconductor switches 105 of the first group 205 may be disposed on the top and the semiconductor switches 105 of the second group 210 may be disposed on the underside of a circuit board to which the semiconductor switches 105 are mechanically and electrically attached, with the heat sinks 125 in opposite directions from the board extend away.

Figure 3 shows a circuit diagram of a three-phase inverter 300. The representation is hybrid, by the semiconductor switch 105 and its compounds are shown as a circuit diagram, while the arrangement of the semiconductor switch 105 is to be interpreted geometrically. The illustrated embodiment is based on the example of FIG. 1. Elements of the three-phase inverter 300 that go beyond the driver board 100 are not shown.

By way of example, a first supply line 305 with a high potential and a second supply line 310 with a low potential are connected. Two semiconductor switches 105 each form a half-bridge between the leads 305 and 310. taps of the half bridges are led out as output lines 315 to 325. With them, for example, a three-phase electric motor can be connected, whose torque, speed or direction of rotation can be controlled by appropriately driving the semiconductor switch 105. Such an electric motor can be used, for example, for control tasks on board a motor vehicle, for example in a steering or brake assistance.

Although the connections between the semiconductor switches 105 are not shown without crossing, it can be seen that the leads 305, 310 and output leads 315 through 325 can be made geometrically similar. In particular, the lengths of corresponding lines 305 to 325 may correspond to each other. In this case, only the parts of the lines 305 to 325 are taken into account, which lie in a radius around the center, not shown, 120, wherein the perimeter touches each of the radially outermost points of the semiconductor switch 105.

FIG. 4 and FIG. 5 each show a circuit diagram of a three-phase inverter 300 extended by a phase separation circuit or a short circuit. The illustration is equivalent to FIG. 3, and therefore the semiconductor switch 105 is referenced to FIG referenced section.

FIG. 4 shows in particular the three-phase inverter 300 with a phase separation circuit comprising three further semiconductor switches 106 designed as phase separators, which are each assigned to a half bridge consisting of two semiconductor switches 105 and electrically coupled thereto. The phase separators 106 are arranged in a plane parallel to the plane comprising the arrangement of the semiconductor switches 105. Preferably, the phase separators 106 are disposed on a different side of a board than the semiconductor switches 105. The respective phase separator 106 is electrically coupled to the corresponding half-bridge via the first 315 or second 320 or third output line 325 assigned to the respective half-bridge. The phase separator 106 is thus provided downstream of the respective half-bridge. The arrangement of the phase separator 106 takes place in a manner corresponding to the arrangement of the semiconductor switch 105 described above Way, wherein the phase separators 106 are arranged in a plan view of the planes on an identical circular line as the semiconductor switch 105, wherein a phase separator 106 between two adjacent semiconductor switches 105 is arranged. According to an alternative embodiment, the phase separators 106 are arranged on a circular line which lies in a plan view of the arrangement levels within the circular line having the semiconductor switches 105. As a result, a more compact arrangement of the semiconductor switches 105 and the phase separator 106 can be achieved. Furthermore, a circuit board including the semiconductor switches 105 and the phase separators 106 may be further equalized in terms of thermal stress.

FIG. 5 shows in particular the three-phase inverter 300 with a short-circuit comprising three further semiconductor switches 107 designed as short-circuiting switches, which are each assigned to a half-bridge consisting of two semiconductor switches 105 and are electrically coupled to this and to each other. The short-circuiting switches 107 are arranged in a plane parallel to the plane comprising the arrangement of the semiconductor switches 105. Preferably, the phase separators 107 are disposed on a different side of a board than the semiconductor switches 105. The respective short-circuit switch 107 is electrically coupled to the line connecting the two semiconductor switches 105 forming a half-bridge and to the other short-circuit switches 107 via a common connecting line 330. The short-circuit switch 107 is thus provided downstream of the semi-bridge forming semiconductor switches 105. The respective short-circuit switch 107 is arranged near its connection point for connection to the respective line in order to use the shortest possible connecting lines. The arrangement of the short-circuiting switch 107 may according to another preferred, not shown embodiment in one of the arrangement of the phase separator 106 corresponding manner described above, if, for example, a cooling of the short-circuit switch 107 should be required.

FIG. 6 shows a side view of an embodiment of the driver assembly 100 of FIG. 1. A circuit board 400 has a top 405 and a bottom 410. On top 405, one or more tracks 415 extend electrically are connected to the semiconductor switch 105. The semiconductor switch 105 is surface-mounted and is also located on the top 405 of the board 400th

A contact portion 420 of the contact surface 130 of the heat sink 125 abuts against a contact surface 425 of the semiconductor switch 105 facing away from the circuit board 400 in order to produce a thermal coupling. For improved heat conduction, electrical insulation or height compensation can be provided between the contact surface 425 and the contact portion 420, a Wärmeleitpad, a thermal paste, a mica screen or other element which preferably has a good heat transfer at preferably the lowest possible electrical conductivity.

The heat sink 125 may include a projection 430 that lies outside the plane 110 that includes the contact portion 420. The protrusion 430 extends toward the board 400 and is thermally coupled to the track 415. In this case, preferably, a conductor track 415 is thermally connected, which comprises a feed line or output line 305 to 325; however, a control line may also be included. Again, between the projection 430 and the track 415 may be provided an element for height compensation, to improve the heat conduction or electrical insulation.

FIG. 7 shows in the upper area a representation of temperatures on a circular arrangement of six semiconductor switches 105, which in the present example are used as driver subassembly 100 for the three-phase inverter 300 of FIG. In the lower part of FIG. 5, a known rectangular arrangement of semiconductor switches 105 is shown.

In the three-phase inverter 300, the semiconductor switches 105 are turned on and off at substantially the same frequencies and duty ratios, so that each semiconductor switch 105 converts practically the same electric power into heat output. Shown is a plan view of the plane 1 10. The semiconductor switches 105 are on their tops in contact with a heat sink 125. Geometric areas whose temperatures fall within a common area are together shown menhängend, with exemplary mean values of the temperature ranges are numerically entered in ° C.

It can be seen that on the circular arrangement illustrated above, the surface of each semiconductor switch 105 includes only a few temperature ranges and that the surfaces of the semiconductor switches 105 have substantially the same temperature ranges. The temperature load of each semiconductor switch 105 and the temperature loads of all semiconductor switches 105 are therefore highly homogeneous. Thereby, aging and failure probabilities of the semiconductor switches 105 of the driver assembly 100 may be substantially equal over their operating times. The semiconductor switches 105 can thereby be dimensioned improved to a predetermined electrical load. This can be advantageous in particular in a safety-critical application, such as in the control of a servomotor, for example for steering or brake assistance on board a motor vehicle.

At the rectangular arrangement shown below, in which adjacent semiconductor switches have unequal distances from one another, the temperatures at the surfaces of the semiconductor switches 105 are higher overall. In addition, the surfaces of the semiconductor switches 105 each include more temperature ranges that are further apart. The semiconductor switches 105 have highly different highest and lowest temperatures. It is expected that the highest temperature load semiconductor switch 105 ages fastest and has the highest probability of failure. However, the aging and probability of failure of each semiconductor switch 105 is difficult to determine due to the large temperature gradients on the surfaces of the semiconductor switches 105, so that the durability of the arrangement shown may be subject to great uncertainty. Furthermore, less power can be permanently switched through this inverter arrangement, since reaching the limit temperature of a single semiconductor switch 105 defines the shutdown or degradation limit of the entire assembly. REFERENCE CHARACTERS

100 driver board

105 semiconductor switch

106 phase separator

107 short-circuit switch

1 10 level

1 15 circle line

120 midpoint

125 heat sink

130 contact area

135 place

140 direction

205 first group

210 second group

300 three-phase inverter

305 first supply line (high potential)

310 second supply line (low potential)

315 first output line

320 second output line

325 third output line

330 connection line

400 board

405 top

410 bottom

415 trace

420 contact section

425 contact surface

430 ahead

Claims

claims

1 . Driver assembly (100) with a plurality of semiconductor switches (105, 106, 107), characterized in that the semiconductor switches (105, 106, 107) are arranged in a plane (1 10) such that distances between adjacent semiconductor switches (105, 106, 107 ) in the plane (1 10) are each the same size and each semiconductor switch (105, 106, 107) the same number of adjacent semiconductor switches (105, 106,

107).

Second driver assembly (100) according to claim 1, characterized in that the semiconductor switches (105, 106, 107) on a circular line (1 15) are evenly distributed.

3. driver assembly (100) according to claim 1 or 2, characterized in that distances between non-adjacent semiconductor switches (105, 106, 107) are at least 1, 5 times as large as distances between adjacent semiconductor switches (105, 106, 107).

4. driver assembly (100) according to claim 1 or 2, characterized in that the semiconductor switches (105, 106, 107) are aligned uniformly to each other.

5. driver assembly (100) according to any one of the preceding claims, characterized in that at least six semiconductor switches (105, 106, 107) are provided and the driver assembly (100) of a three-phase inverter (300) is included.

6. Driver assembly (100) according to claim 5, characterized in that nine semiconductor switches (105, 106, 107) are provided, wherein two semiconductor switches (105) each form one of the three phases associated half-bridge and each half-bridge with a third semiconductor switch (106; 1 07) is electrically coupled.

7. driver assembly (100) according to claim 6, characterized in that the third semiconductor switch (107) via a common connection line (300) are electrically coupled to each other.

8. driver assembly (100) according to claim 6 or 7, characterized in that the third semiconductor switch (107) are arranged in a different plane than the semi-bridge forming semiconductor switch (105).

9. driver assembly (100) according to any one of the preceding claims, characterized by a heat sink (125) for thermal coupling with the semiconductor switches (105, 106, 107), wherein the heat sink a plurality of in a respective plane (1 10) lying contact portions (420) for engagement with the semiconductor switches (105, 106, 107).

The driver assembly (100) of claim 9, wherein the contact portions (420) are comprised of a contact surface having the shape of a circular disk.

1 1. The driver assembly (100) of claim 9, wherein the contact portions (420) are comprised of a contact surface (130) having the shape of a regular polygon with as many corners as in-plane semiconductor switches (105, 106, 107) on the heat sink (FIG. 125).

12. Driver assembly (100) according to one of claims 9 to 11, characterized in that the semiconductor switches (105; 106; 107) comprise surface-mounted components, wherein the semiconductor switches (105; 106; 107) are electrically contacted by conductor tracks (415) and the heat sink (125) comprises a projection (430) located outside the plane (1 10) for thermal coupling to at least one conductor track (415).

13. driver assembly (100) according to any one of the preceding claims, characterized in that conductor tracks (415) for the electrical connection of terminals of the semiconductor switches (105; 106; 107) have substantially equal surfaces.

14. Driver assembly (100) having a predetermined number of semiconductor switches (105), characterized in that each semiconductor switch (105) one of at least two driver assemblies (100) is assigned according to one of the preceding claims.