DE102022204400A1 - Inverter with at least one half bridge - Google Patents

Abstract

The invention relates to an inverter (1) with at least one half-bridge (10), the half-bridge (10) having at least one high-side transistor (11) and at least one low-side transistor (12), the half-bridge (10 ) is connected to at least one heat sink, the heat sink being designed as a cuboid ceramic (16) which has at least one coolant channel (17), the at least one high-side transistor (11) being on a top side (O) of the Ceramic (16) is arranged and the at least one low-side transistor (12) is arranged on an opposite underside (U), the ceramic (16) being partially metallized, the metallizations (13-15) being at least the input and form outputs of the half bridge (10).

Description

The invention relates to an inverter with at least one half bridge.

Inverters have a wide range of applications. One area of application is use in the traction networks of a motor vehicle. For example, a 400 V - 800 V DC voltage is typically converted into a three-phase AC voltage in order to drive a three-phase electric machine. Due to the switching processes, there is considerable heat loss in the power transistors.

From the DE 10 2020 203 546 A1 is a cooling arrangement for a power converter, in particular a pulse inverter, known, with a first cooling module and at least one further cooling module and a fluid delivery device. Furthermore, at least one fluid line is provided, which is designed to introduce a cooling fluid mass flow generated by the fluid delivery device into or out of the cooling modules, the first cooling module and the further cooling module being positioned opposite one another, so that a power module of the power converter can be accommodated between them is. Furthermore, the cooling fluid mass flow can be guided through the fluid line and/or the cooling modules in such a way that a higher heat absorption occurs in an area of the first cooling module facing the power module than in an area of the further cooling module facing the power module.

From the EP 3 206 468 A1 a converter with a DC intermediate circuit for converting an input voltage into an AC voltage with a predetermined amplitude and frequency for controlling a single or multi-phase load is known, with a number of modules designed to be stackable one on top of the other, each module comprising a ceramic heat sink with a receiving surface on which electronic components of a phase are accommodated, the ceramic heat sink in the area of the receiving surface having one or more channels through which a cooling medium can flow during operation of the converter.

From the DE 10 2018 202 484 A1 Power electronics are known, comprising a heat sink, at least two half-bridge modules mounted on one side of the heat sink, a circuit board mounted on the half-bridge modules, and at least one capacitor mounted on the circuit board. Furthermore, each half-bridge module has a housing that has a cooling side that is mounted on the heat sink. The housing has a connection side from which a plurality of connection pins protrude for each DC voltage connection of the half-bridge module, which are connected to the circuit board, with conductors in the circuit board being designed to connect the half-bridge modules in parallel and to form an intermediate circuit with the at least one capacitor connect. The power electronics arrangement further comprises at least two opposing half-bridge modules mounted on an opposite side of the heat sink.

The invention is based on the technical problem of creating an inverter that has a compact design with good cooling performance.

The solution to the technical problem results from an inverter with the features of claim 1. Further advantageous embodiments of the invention result from the subclaims.

For this purpose, the inverter has at least one half-bridge, which has at least one high-side transistor and at least one low-side transistor, the half-bridge being connected to at least one heat sink. The heat sink is designed as a cuboid ceramic that has at least one coolant channel. The at least one high-side transistor is arranged on an upper side of the ceramic and the at least one low-side transistor is arranged on an opposite underside. The ceramic is partially metallized, with the metallization forming at least the inputs and outputs of the half bridge. This allows a very compact design to be created where the two halves of the half bridge are cooled evenly, with the connections being very short so that parasitic inductances are minimized. In addition, this arrangement allows further advantageous configurations, which will be explained later. The metallizations are preferably made of copper. The ceramic can also have several coolant channels, possibly with an internal structure. The high-side and low-side transistors are preferably attached to the ceramic as bare chips, for example soldered or sintered, which improves the dissipation of heat loss and increases compactness.

In one embodiment, the inverter has three half-bridges, with the high-side transistors of all half-bridges arranged on the top of a common ceramic and the low-side transistors of all half-bridges on the opposite bottom of the common ceramic, further compressing the design. but places certain demands on the length of the ceramic. But it can also be provided that For example, the high-side transistors of the first and third half-bridge and the low-side transistor of the second half-bridge are arranged on the top of the ceramic and accordingly the high-side transistor of the second half-bridge and the low-side transistors of the first and third half bridge are arranged on the bottom.

In an alternative embodiment, the inverter has three half-bridges, with the half-bridges being arranged on different ceramics. It can further be provided that the three ceramics are cast, with the coolant channels being arranged in alignment with one another and the ceramics being arranged in abutment with one another. This ensures that only one coolant pump is required, with the requirements for the production of the ceramic being reduced.

In a further embodiment, the half bridge is assigned at least one short-circuit ring, which is formed by a circumferential metallization on the ceramic. This short-circuit ring reduces the parasitic inductance of the half-bridge on the DC side by opposing magnetic fields as a result of the currents induced in it, so that voltage peaks due to the switching processes are reduced.

In a further embodiment, the at least one short-circuit ring is electrically connected to the AC voltage connection of the half bridge.

In a further embodiment, the half bridge has four high-side transistors and four low-side transistors, with the four high-side transistors and the four low-side transistors each being connected in parallel, with the high-side transistors being connected in parallel. Transistors and the low-side transistors are arranged in two rows, with the metallization of the positive DC voltage connection and the metallization of the AC voltage connection being structured in such a way that there is a central feed point for all high-side transistors and a central feed point for all low-side -Transistors results. This symmetrizes the current flow.

In a further embodiment, the metallization of the AC voltage connection has two T-shaped structures, which are arranged left and right on the high-side transistors and/or left and right on the low-side transistors, so that the current flow is symmetrical because the connection lengths are symmetrical.

In a further embodiment, the DC voltage connections have metallic tabs. These tabs can be formed from the ceramic and metallized or they can be separate components that are, for example, soldered to the metallization of the ceramic. The tabs are preferably designed in such a way that they are at a very small distance from one another, so that the connections of an intermediate circuit capacitor between the two connections are very short and span a small area, so that parasitic inductances are reduced. The intermediate circuit capacitor is preferably pushed between the tabs so that the area spanned between the connections is reduced to a minimum.

In a further embodiment, gate driver circuit boards are arranged on the ceramic. The connection from the gate driver circuit boards to the high-side and low-side transistors can be made using bonding wires or routed through the ceramic.

The high-side and low-side transistors are preferably designed as silicon carbide (SiC) MOSFETs. If several transistors (e.g. four or six) are connected in parallel, they can be controlled in the same way by connecting all gate connections to one another (possibly via resistors). Alternatively, it is possible to control the transistors independently of each other, which allows greater flexibility for setting the voltage curves.

A preferred area of application is use in a traction network of a motor vehicle.

• 1 eine schematische Darstellung einer Halbbrücke mit einem Zwischenkreiskondensator,
• 2 eine schematische Darstellung einer Halbbrücke auf einer Keramik in einer perspektivischen Draufsicht,
• 3 eine schematische Darstellung der Halbbrücke gemäß 2 in einer perspektivischen Unteransicht,
• 4 eine Detailansicht der Gleichspannungsanschlüsse,
• 5 eine alternative Ausführungsform mit gebogenen Laschen,
• 6 eine Seitenansicht einer alternativen Ausführungsform,
• 7 eine Draufsicht auf die Ausführungsform gemäß 6,
• 8 eine Draufsicht auf eine weitere Ausführungsform mit drei Halbbrücken und
• 9 eine Draufsicht auf eine weitere Ausführungsform mit drei Halbbrücken.

The invention is explained in more detail below using a preferred exemplary embodiment. The figures show:

• 1 a schematic representation of a half bridge with an intermediate circuit capacitor,
• 2 a schematic representation of a half bridge on a ceramic in a perspective top view,
• 3 a schematic representation of the half bridge according to 2 in a perspective bottom view,
• 4 a detailed view of the DC voltage connections,
• 5 an alternative embodiment with curved tabs,
• 6 a side view of an alternative embodiment,
• 7 a top view of the embodiment according to 6 ,
• 8th a top view of another embodiment with three half bridges and
• 9 a top view of another embodiment with three half bridges.

In the 1 A half bridge 10 is shown in very simplified form, which consists of four high-side transistors 11 connected in parallel and four low-side transistors 12 connected in parallel. The drain connections of the high-side transistors 11 are connected to a positive DC voltage connection DC+ and the source connections of the low-side transistors 12 are connected to a negative DC voltage connection DC-. The center taps are connected to an AC voltage connection AC-OUT.

The bars with the different hatchings are intended to help to better assign the different metallizations 13, 14, 16 in the following figures. The advantage of using several transistors connected in parallel is that the currents are divided. Particularly with SiC transistors, the previously available chip areas are not sufficient to switch, for example, 150 kW of power without parallelization. Using multiple transistors in parallel circumvents this problem. For reasons of simplicity, gate control is not shown here. The gates of all high-side transistors 11 can receive a common control signal (as in 1 shown as an example) or can be controlled independently of one another. The same applies to the gates of the low-side transistors 12. Also shown is an intermediate circuit capacitor C, which lies between the DC voltage connections DC+, DC-.

In 2 and 3 a half bridge 10 is shown on a ceramic 16 as a heat sink. The ceramic 16 is cuboid and has coolant channels 17 through which coolant can be pumped through the ceramic 16 by a pump (not shown). The four high-side transistors 11 are arranged on an upper side O and the four low-side transistors 12 on an opposite underside U, with the coolant channels 17 extending from the end faces 18 through the ceramic 16. The invisible drain connections located on the underside of the transistor are connected to the metallization 13, the source connections S being connected to the metallization 15 of the alternating voltage by bonding wires 19 (four bonding wires are shown for each source connection S). AC-OUT connection.

Accordingly, the invisible drain connections of the low-side transistors 12 located on the underside of the transistor are connected to the metallization 15 of the AC voltage connection AC-OUT and the source connections S are connected to the metallization 14 via bond wires 19 . The direct voltage connections DC+, DC- and the alternating voltage connection AC-OUT each have tabs 20-22 which protrude over the cuboid part of the ceramic, whereby the tabs 20-22 can be separate parts or can be made from the metallization of the ceramic 16 can be formed. The metallizations 13-15 are preferably made of copper. Also shown are three gate connections G of the transistors 11, 12, which are either connected to external connections of the power module or are also connected via bonding wires to gate driver components, which are preferably arranged on a circuit board, which is also on the ceramic 16 is arranged. Also shown is a circumferential closed short-circuit ring 23, which is connected to the AC voltage connection AC-OUT and is part of the metallization 15. The high-side transistors 11 and the low-side transistors 12 are preferably bare chips without a housing and are connected directly to the metallizations 13, 15 by soldering or sintering.

In the 4 the tabs 20-22 are shown enlarged, with only three high-side transistors 11 with the bonding wires 19 being shown on the top side O. The short-circuit ring 23 is also shown, although the coolant channels are not shown for reasons of simplicity. The tabs 20, 21 are brought towards one another in order to reduce their distance in order to connect the intermediate circuit capacitor C (see 1 ) to be connected with low inductance.

In the 5 An alternative embodiment of a half bridge 10 is shown, each with six high-side and six low-side transistors. The tabs 20, 21 are angled vertically. An inlet 24 and an outlet 25 of the ceramic 16 for the coolant are also shown. Two short-circuit rings 23 are applied to the ceramic 16, which are again connected to the metallization of the AC voltage connection AC-OUT, which is advantageous, but not mandatory.

In 6 and 7 Another alternative design is shown, with the half bridge 10 again having six high-side transistors and six low-side transistors, with the coolant channels not being shown for the sake of simplicity and the individual bonding wires 19 being shown as rails . The special thing is that the two tabs 20, 21 of the DC+, DC- voltage connections are brought together very tightly, so that the intermediate circuit capacitor C can simply be pushed in between.

In the 8th an inverter 1 is shown which has three half bridges 10. Each half bridge 10 has four high-side transistors 11, each of which is arranged in two rows. The same applies to the low-side transistors 12. Each half bridge 10 has two short-circuit rings 23. The metallization 13 is structured in such a way that a central feed point 25 results, so that the current flow into the transistors is symmetrized.

In the 9 an inverter 1 is shown, which is basically as in 8th is constructed. In addition, the metallization 15 has a T-shaped structure 26 to the left and right of the high-side transistors 11, the T-shaped structures 16 being connected to the short-circuit rings 23. This symmetrizes the source current of the high-side transistors 11. The design for the low-side transistors 12 is analogous.

Reference symbol list

1

Inverter

10

Half bridge

11

High side transistor

12

Low side transistor

13

Metallization

14

Metallization

15

Metallization

16

Ceramics

17

Coolant channel

18

front side

19

Bond wire

20

tab

21

tab

22

tab

23

Short circuit ring

24

inlet

24

outlet

25

Entry point

26

T-shaped structure

O

Top

U

bottom

S

Source connection

G

Gate connector

DC+

DC voltage connection

DC

DC voltage connection

AC OUT

AC voltage connection

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102020203546 A1 [0003]
• EP 3206468 A1 [0004]
• DE 102018202484 A1 [0005]

Claims (10)

Inverter (1) with at least one half-bridge (10), the half-bridge (10) having at least one high-side transistor (11) and at least one low-side transistor (12), the half-bridge (10) having at least one Heat sink is connected, the heat sink being designed as a cuboid ceramic (16) which has at least one coolant channel (17), characterized in that the at least one high-side transistor (11) is on a top side (O) of the ceramic (16) is arranged and the at least one low-side transistor (12) is arranged on an opposite underside (U), the ceramic (16) being partially metallized, the metallizations (13-15) at least the input and Form outputs of the half bridge (10). Inverter after Claim 1 , characterized in that the inverter (1) has three half-bridges (10), the high-side transistors (11) of all half-bridges being on the top side (O) of a common ceramic (16) and the low-side transistors (12 ) of all half bridges (10) are arranged on the opposite underside (U) of the common ceramic (16). Inverter after Claim 1 , characterized in that the inverter (1) has three half-bridges (10), the half-bridges (10) being arranged on different ceramics (16). Inverter according to one of the preceding claims, characterized in that the half bridge (10) is assigned at least one short-circuit ring (23), which is formed by a circumferential metallization on the ceramic (16). Inverter after Claim 4 , characterized in that the at least one short-circuit ring (23) is electrically connected to the alternating voltage connection (AC-OUT) of the half bridge (10). Inverter according to one of the preceding claims, characterized in that the half bridge (10) has four high-side transistors (11) and four low-side transistors (12), the four high-side transistors (11) and the four low-side transistors (12) are each connected in parallel, the high-side transistors (11) and the low-side transistors (12) being arranged in two rows, the metallization (13) of the DC voltage connections ( DC+) and the metallization (15) of the AC voltage connection (AC-OUT) is structured in such a way that there is a central feed point (25) for all high-side transistors (11) and a central feed point for all low-side transistors (12) trains. Inverter after Claim 6 , characterized in that the metallization (15) of the AC voltage connection (AC-OUT) each has two T-shaped structures (26), which are left and right on the high-side transistors (11) and / or left and right from the low-side transistors (12) are arranged. Inverter according to one of the preceding claims, characterized in that the DC voltage connections (DC+, DC-) have metallic tabs (20, 21). Inverter after Claim 8 , characterized in that at least one intermediate circuit capacitor (C) is inserted between the tabs (20, 21). Inverter according to one of the preceding claims, characterized in that gate driver circuit boards are arranged on the ceramic (16).

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