EP3417538A1

EP3417538A1 - Converter

Info

Publication number: EP3417538A1
Application number: EP17702562.4A
Authority: EP
Inventors: Martin Schulz
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2016-02-17
Filing date: 2017-01-25
Publication date: 2018-12-26
Also published as: US20210211061A1; DK3208925T3; WO2017140464A1; EP3208925B1; EP3208925A1; CN108702097A

Abstract

The invention relates to a converter for converting an input voltage (U₁) applied between two input terminals (101, 102) into an alternating voltage with pre-determined amplitude and frequency for controlling a single-phase or multi-phase load, with at least two series-connected submodules (SM; SM1,…,SM8) of an inverter arm. Each submodule (SM; SM1,…,SM8) comprises a circuit carrier (11) and at least two controllable switching elements (S₁, S₂) which are electrically connected to each other on the circuit carrier (11). Furthermore, each submodule (SM; SM1,…,SM8) comprises a first submodule terminal (X1) and a second submodule terminal (X₂). In said converter, first main terminals (D) of the controllable switching elements (S₁, S₂) of the at least two submodules (SM; SM1,…,SM8) are thermally connected to a cooling surface of a cooling body (12). Furthermore, the second submodule terminal (X₂) of a first of the at least two submodules (SM; SM1,…,SM8) is connected to the first sub-module terminal (X₁) of a second of the at least two submodules (SM; SM1,…,SM8). The converter is characterised in that the connection of the second submodule terminal (X₂) of the first submodule (SM; SM1,…,SM8) to the first submodule terminal (X₁) of the second submodule is carried out by a conductive layer (16), e.g. a metal rail, applied to the cooling surface.

Description

The invention relates to a converter for converting an input voltage applied between two input terminals into an alternating voltage having a predetermined amplitude and frequency for driving a single- or multi-phase load, having at least two submodules of an inverter arm connected in series with one another.

Modern modular converter topologies with multilevel characteristics consist of identically structured functional units, which are referred to as submodules and are constructed either as half-bridge or full-bridge submodules. These are connected in series to provide an inverter phase. The interconnection of a large number of half-bridge submodules in series takes up a large amount of installation space. This ensures high costs of the inverter.

In the low voltage area, it is common to build modular topologies, generally circuit board based, submodules with discrete power semiconductor switching elements.

The use of printed circuit boards results in further problems due to the limited current carrying capacity of the printed circuit boards and, compared to power ^modules in which the power semiconductor switching elements are applied directly to a carrier (so-called direct copper bonding (DCB)), poorer cooling conditions. In the connection cables and the contact points between connecting cables and printed circuit boards, significant current heat losses occur, which must be dissipated.

The electrical connection between the discrete power semiconductor switching elements and the screw or terminal contacts of the cable is realized via copper tracks on the Schaltungsträ ^¬ like. So that the current carrying capacity required can be ensured ge ^¬ come expensive Hochstromschaltungsträ- ger used. These are known as thick copper boards or boards with inserted copper profiles.

The heat dissipation in a PCB-based converter takes place directly at a main connection (usually the

Drain or collector terminal of the power semiconductor switching element). For this purpose, the power semiconductor switching element is pressed di ^¬ rectly with its large-area connection contact to a heat sink. In order to avoid an electrical connection between the terminal contact and the heat sink, an insulator is arranged between these two surfaces.

The current heat losses in the connection cables and in the contact points can be minimized and dissipated by larger cable cross-sections and larger contacts verwen ^¬ det. However, this in turn means that the construction and connection technology is very large and heavy.

Nevertheless, the circuit-board-based realization of an inverter is often preferred over DCB-based converters, since such an inverter has better electrical properties.

It is therefore an object of the present invention to provide a converter, which is structurally and / or functionally improved.

This object is achieved by a converter according to the features of claim 1. Advantageous embodiments will be apparent from the dependent claims.

A converter is proposed for converting an input voltage applied between two input terminals into an alternating voltage of predetermined amplitude and frequency for driving a single- or multi-phase load, comprising at least two submodules of an inverter arm connected in series with each other, each submodule comprising the following a circuit carrier; at least two controllable Switching elements which are electrically interconnected on the circuit carrier; a first submodule port; a second submodule connection. First main terminals of the controllable switching elements of the at least two submodules are thermally connected to a cooling surface of a heat sink. The second Submodulanschluss a first of the at least two sub-modules is connected to a first Submodulanschluss one of the at least two half-bridge two submodules ^¬ th. The converter is characterized in that the connection of the second submodule connection of the first submodule to the first submodule connection of the second submodule is realized by a conductive layer applied to the cooling surface.

This makes it possible, an inverter bereitzustel ^¬ len, in which the sub-modules based PCBs are built. This makes it possible to provide good electrical properties of the submodules and of the converter as a whole. At the same time, the connection of the submodule connections via a conductive layer applied to the cooling surface enables a good heat dissipation of the heat arising in operation in the semiconductor switching elements. In particular, this structure makes it possible to cool the electrical contacts directly.

By exclusively contacting the submodules via the first main terminals of the two switching elements, the series connection of the submodules can be made very compact. In particular, the mounting effort is minimized. Furthermore, a direct cooling of the electrical contacts and the conductive layer is realized.

Another advantage is that a reduced current flow occurs on the circuit ^¬ carrier of the submodules compared to a conventional submodule, since the current is removed directly via the first main terminals of the switching elements. This results in an advantageous lower thermal ^¬ cal stress of the circuit carrier. According to an expedient embodiment, the first main terminals of the switching elements surface contacts, which are vollflä ^¬ chig applied to the conductive layer. This not only ensures a high current carrying capacity. Rather, the heat transfer in the direction of the conductive layer and of the heat sink can also take place via the first main connections of the heat transfer in the switching elements. In addition, the manufacturability is facilitated because the first main terminals in a simple manner on the conductive

Layer can be connected to the heat sink. It should be emphasized that commercially available discrete power semiconductor switching elements can be used as switching elements of the submodules.

According to a further expedient embodiment, the first main terminals of the switching elements are non-positively

and / or cohesively connected to the conductive layer. This ensures a good current-carrying capacity between the first main terminals of switching elements of adjacent submodules via the conductive layer. Gleichzei ^¬ tig a good heat transfer is ensured to the heat sink. According to a further expedient embodiment, the conductive layer is a metal rail, which is connected via the insulation ^¬ layer with the heat sink.

A further advantageous embodiment provides that the electrical connection, ie, the node between the second main terminal of the first switching element and the ers ^¬ th main terminal of the second switching element of a jeweili ^¬ gen submodule via one or implemented plurality of conductive paths of the sound ^¬ tung carrier of the submodule is , For this purpose, the circuit carrier, for example, so-called. Dickleiterbahnen (ie conductor thicknesses greater than 400 μιη) have. A further embodiment provides that between the two input terminals per phase two inverters serially ver arms are ^¬ switches, wherein a node point between the two

Inverter arms is coupled to an output terminal of an inverter phase. In particular, the inverter comprises per

Inverterarm and phase at least two submodules.

According to a further expedient embodiment, a respective submodule comprises a half bridge with two controllable and serially interconnected switching elements. The first submodule connection is electrically connected to a first main connection of a first of the at least two switching elements (high-side switching element). The second Submodulanschluss is elec trically ^¬ connected to a node of a second main terminal of the first switching element and a first main terminal ei ^¬ nes second of the at least two switching elements (low-side switching element).

According to a further expedient embodiment, the submodule comprises a full bridge with two parallel connected

Half bridges, wherein in a first of the half bridges, a first and a second switching element are connected in series and in a second of the half bridges, a third and a fourth switching element are connected in series. The first submodule terminal is electrically connected to a node of a second main terminal of the first switching element and a first main terminal of the second switching element. The second Submodulanschluss is electrically connected to a node of a second main terminal of the third switching element and a first main terminal of the fourth switching element ver ^¬ prevented. The first main terminals of the first and third switching elements are electrically connected to each other via a further conductive layer on the cooling surface. In this variant, it is expedient if the further routing ^¬ compatible layer between the conductive layers of the first and second Submodulanschlusses on the cooling body is arranged ^¬ is. The invention is explained in more detail below with reference to an exporting ^¬ approximately embodiment in the drawing. 1 shows the serial connection of a number of submodules for providing an inverter phase between an input terminal and an output terminal; Fig. 2 is an electrical equivalent circuit of a Halbbrü ^¬ CKEN sub-module;

3 shows a schematic representation of two half-bridge submodules arranged on a heat sink in a conventional design variant; and

Fig. 4 is a schematic representation of a plurality of half-bridge submodules on a heat sink in an embodiment of the invention.

1 shows an inverter phase of a converter in a so-called multi-level topology. In this example, eight identically constructed submodules SM1, SM8 are interconnected between an input terminal 101 and an input terminal 102. A node 103 between the half-bridge sub-modules SM4 and SM5 is connected to an output terminal 104 of the inverter phase. The submodules SM1, SM4 interconnected between the input terminal 101 and the node 103 are assigned to an upper inverter arm. The intermediate see the node 103 and the input terminal 102 seri ^¬ ell interconnected submodules SM1, SM8 are associated with a lower Inverterarm. Between the input terminals 101 and 102 is applied to a DC voltage Ui. The input terminals 101, 102 are connections of a DC voltage intermediate circuit (not shown here). By a just ^¬ if not shown control circuit, which controls the contained in the respective sub ^¬ modules SM1, SM8 switching elements and switch in a suitable manner conductive and blocking tet, can be tapped at the output terminal 104, an AC voltage.

2 shows an electrical equivalent circuit diagram of the identically constructed submodules SM1, SM8 in the form of a half-bridge submodule. Thus, each of the half-bridge submodules SM comprises two series-connected switching elements Si, S ₂ . The switching elements Si, S2 are for example

MOSFETs or other controllable semiconductor switching elements. The drain D as designated first main terminal of the switch Tele ^¬ ments Si is connected to a first Submodulanschluss Xi. The second main terminal of the

Switching element Si is connected to the drain terminal D of the second switching element S2. The node between the source terminal S of the switching element Si and the drain terminal of the switching element S2 forms a second Submo ^¬ dulanschluss X2 · The source terminal of the second shawl Tele ^¬ ments S2 is through a capacitor C _SM to the drain terminal of the first Switching element Si connected. Parallel to the capacitor C _SM , an optional output network NW can be connected to the nodes marked with the reference symbols P and N.

To provide an inverter phase with multilevel characteristics, as shown in FIG

Submodule connections Xi, X2 of the respective half-bridge Submodu ^¬ le connected in series with each other. Thus, as can easily be deduced from FIG. 1, the first submodule connection Xi of the submodule SM1 is connected to the input connection 101. The second submodule connection X2 of the submodule SM1 is connected to the first submodule connection Xi of the submodule SM2. The second submodule connection X2 of the submodule SM2 is in turn connected to the first submodule connection of the submodule SM3, etc. The second submodule connection X2 of the submodule SM8 is finally connected to the input connection 102. 1, the output terminal 104 is the inverter phase of the converter 1 via the node 103 both with the second submodule connection X2 of the submodule SM4 and also connected to the first submodule connection Xi of the submodule SM5.

This interconnection takes in the inverter 1 a lot of space in claims. FIG. 3 shows a possible design variant for two printed circuit board-based submodules SM1, SM2 arranged adjacently on a heat sink 12. In this design variant, each submodule SM1, SM2 is constructed using discrete power semiconductor switching elements and a circuit carrier. This results in better electrical properties compared to the known from the prior art direct copper bonding (DCB).

The sub-modules SM1, SM2 (applicable in a corresponding manner, this na- Türlich also for the other, in Fig. 3, not shown, submodules SM3, SM8) each comprise a Schaltungsträ ^¬ ger 11. On the circuit substrate 11 are two power semiconductors switching elements 10 applied , Each of the power semiconductor switching elements comprises three contact pins, which are plugged and soldered through corresponding openings or bores of the circuit carrier 11 (not shown in detail in FIG. 3). The three contact pins represent the drain terminal D (first main terminal), the source terminal S (second main terminal) and the gate terminal G (control terminal). An electrical connection between the source terminal of the power semiconductor marked Si. Switching element 10 and the drain terminal of the gekenn ^¬ marked with S2 ^¬ power semiconductor switching element 10 via a conductor 14. Due to the high current flowing here, the conductor 14 may be formed as a thick copper conductor. The electrical connection between the source terminal S of Si and the drain terminal D of S2 forms the second submodule connection X2 explained in connection with FIG. 2. The first submodule connection Xi is the drain terminal D of the power semiconductor circuit labeled Si. switching element 10. The heat dissipation of the power semiconductor switching elements 10 it ^¬ follows directly to the drain terminals D by direct pressing of the formed on the back of the discrete power semiconductor switching elements 10 drain terminals D of the above-mentioned heat sink 12. In order to short-circuit the drain terminals D via the To avoid heat sink 12, a good thermal conductivity insulating layer 13 is applied to the viewer facing side of the heat sink 12. For a close contact between the backside contacts

To ensure (drain terminals) of the power semiconductor switching elements 10 and the heat sink 12, the power semiconductor switching elements, for example, be screwed onto the heat sink 12 ^¬ . In order to produce the electrical connection between the second submodule connection X2 of the submodule SM1 and the first submodule connection Xi of the submodule SM2, a cable 15 is used in the arrangement according to FIG. This is screwed, for example, between corresponding contact surfaces of the circuit carrier 11 electrically in the manner shown in Fig. 3. Due to the current heat losses occurring at the contact points between the cable 15 and the respective circuit carriers 11 of the half-bridge submodules SM1, SM2 large cable cross-sections and large contacts are used. However, this leads to the construction and connection technology being very large and heavy.

Fig. 4 shows a construction variant according to the invention. In the illustration of FIG. 4, the switching module SM1 is shown in part as well as the switching modules SM2 and SM3 connected in series with it. The marked in Fig. 3 by the reference numeral 15 electrical connection is replaced in each case in the OF INVENTION ^¬ to the invention build variant, by a conductive layer 16, which semiconductor switching elements between the discrete power 10 and the insulating layer 13 is arranged on the cooling body 12. In this case, the drain connection of the second switching element S2 of a half-bridge submodule (eg SM1) and the drain connection of the first switching element elements Si of the adjacent half-bridge submodule (SM2) applied to the conductive layer 16 and electrically conductively connected thereto. Similarly, the drain terminal of the second switching element S2 of the half-bridge sub-module SM2, and the drain terminal D of the first shawl Tele ^¬ ment Si of the adjacent half-bridge submodule (here: SM3) applied to another conductive layer. On a respective conductive layer 16, respectively paarwei ^¬ se, the drain terminals of the switch elements of adjacent half bridge sub-modules are thus applied.

By exclusively contacting the drain terminals D of the half-bridge submodules SM of the discrete power semiconductor switching elements, the series connection of the half-bridge submodules can be made very compact. In particular, results in a compact series circuit with minimal mounting effort. It is a direct cooling of the electrical ^¬ rule contacts and the electrical layers possible. The electrical layers are realized, for example, in the form of metal rails.

The node or output terminal can be realized with the aid of the conductive layer. Thus, the conductive layer can, for example, a pointing away from the circuit carriers tab (not shown), so that a screw connection or plug-in connection can be made at the output terminal in FLAE ^¬ chenbereich the tab.

This results in a reduced current flow via the respective gene circuit carrier of the half-bridge submodules, as a large ^¬ part of the current is taken directly to the drain terminals of the power semiconductors switching elements. This results in a lower thermal stress on the respective circuit carrier.

The inventively proposed Aufbauva ^¬ variant is characterized in that all contact points (ie, the drain terminals of the power semiconductor switching elements) at the same time are those points at which the heat of the power semiconductor switching elements is dissipated. Thus it ^¬ followed by a lifting of the previous separation of electrical and thermal paths. Rather, these are now more consistent.

The cooling of the semiconductor switching elements to the heat sink 12 is only minimally affected by the electrically conductive layer 16, since these can be provided with a very high thermal conductivity value. Preferably, the conductive layers 16 are made of copper or aluminum or alloys thereof.

In the present exemplary embodiment, the invention has been described in FIGS. 2 to 4 with reference to half-bridge submodules of an inverter phase. The inventive principle can be worn on full bridge submodules over ^¬ readily. A full-bridge submodule comprises four switching elements in two parallel paths, whereby two of the switching elements are connected in series to each other. In such a full-bridge submodule, the drain terminals of the two high-side switching elements are connected on a common electrically conductive layer. In contrast, the low-side switching elements are connected to switching elements of two respectively adjacent full-bridge submodules via a conductive layer.

Claims

claims

An inverter for converting an input voltage (Ui) applied between two input terminals (101, 102) into an alternating voltage having a predetermined amplitude and frequency for driving a single- or multi-phase load, comprising at least two submodules (SM, SM1,. , SM8) of an inverter arm, each submodule (SM, SM1, ..., SM8) comprising:

a circuit carrier (11);

at least two controllable switching elements (S i, S ₂ ), which are electrically connected to one another on the circuit carrier (11);

a first submodule port (Xi);

a second submodule port (X ₂ );

in which

first main terminals (D) of the controllable switching elements (S i, S ₂ ) of the at least two submodules (SM, SM1, ..., SM8) are connected in a thermally flat manner to a cooling surface of a heat sink (12);

the second Submodulanschluss (X ₂₎ of a first of the at least two submodules ^¬ (SM; SM1, ..., SM8) with the first Submo ^¬ dulanschluss (Xi) of a second of the at least two Submo ^¬ modules (SM; SM1, .. , SM8);

characterized in that

the connection of the second Submodulanschlusses (X ₂₎ of the f ^¬ th sub-module (SM, SM2, ..., SM8) with the first Submodulanschluss (Xi) of the second sub-module (SM; SM1, ..., SM7) by one on the Cooling surface applied conductive layer (16) is rea ^¬ lisiert.

2. Converter according to claim 1, characterized in that the first main terminals (D) of the switching elements (S i, S ₂ ) are surface contacts, which are applied over the entire surface of the conductive layer (16).

3. Converter according to claim 1 or 2, characterized in that the first main terminals (D) of the switching elements (S i, S ₂ ) are non-positively and / or materially connected to the leitfähi ^¬ gene layer (16).

4. Converter according to one of the preceding claims, characterized in that the conductive layer (16) is a metal ^¬ rail, which is connected via an insulating layer (13) to the heat sink (12).

5. Converter according to one of the preceding claims, characterized in that the electrical connection between the second main terminal (S) of the first switching element (S i) and the first main terminal (D) of the second switching element (S ₂ ) of a respective half-bridge sub-module ( SM, SM1, ..., SM8) via one or more tracks of the circuit carrier (11) of the half-bridge submodule is realized.

6. Converter according to one of the preceding claims, characterized in that between the two input terminals per phase two inverter arms are connected in series, wherein a node between the two inverter arms is coupled to an output terminal of an inverter phase.

7. Converter according to claim 6, characterized in that it comprises at least two submodules (SM, SM1, ..., SM8) per inverter arm and phase.

8. Converter according to one of claims 1 to 7, characterized in that

a respective sub-module (SM; SM1, ..., SM8) comprises a half-bridge with two series-connected controllable and scarf Tele ^¬ segments (Sl, S2);

the first submodule terminal (XI) is electrically connected to a first main terminal (D) of a first of the at least two switching elements (Sl, S2);

- The second submodule terminal (X2) electrically with a

Node of a second main terminal (S) of the first switching element (Sl) and a first main terminal (D) a second of the at least two switching elements (S2) is ver ^¬ connected.

9. Converter according to one of claims 1 to 7, characterized in that

sub-module (SM; SM1, ..., SM8) a full-bridge with two pa ^¬ rallel interconnected half bridges, wherein a first and a second switching element are connected in series in a first of the half-bridge and a third in a second of the half-bridge and a fourth switching element are connected in series;

the first sub-module terminal (Xi) is electrically connected to a node of a second main terminal (S) of the first switching element and a first main terminal (D) of the second switching element;

the second Submodulanschluss (X ₂₎ electrically connected to a node of a second main terminal (S) is connected to the drit ^¬ th switching element and a first main terminal (D) of the fourth switching element;

the first main terminals (D) of the first and third switching elements are electrically connected to each other via a further conductive layer on the cooling surface.

10. Converter according to claim 9, characterized in that the further conductive layer between the conductive

Layers of the first and second submodule terminal (Xi, X ₂ ) is arranged on the heat sink.