DE9403108U1 - Low-inductance high-current busbar for converter modules - Google Patents

Description

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Siemens AG

Low-inductive high-current busbar for power converter modules 5

The invention relates to a single-phase or multi-phase power converter module, consisting of at least one branch pair with two power semiconductors each, which are each arranged between two power connections, wherein each branch pair is assigned a relief network consisting of capacitors, diodes and resistors.

A low-inductance busbar system of a phase module of an inverter is known from DE 36 09 065 Al. The phase module consists of two power semiconductors that can be switched off, each of which is assigned a freewheeling diode and a relief network consisting of a capacitor, a diode and a resistor. The resistors are combined in a resistor. These components form together with the power semiconductors that can be switched off, three dependent circuits. The low-inductance busbar system consists of several busbars that are layered on top of one another and are electrically separated from one another by insulation. For n busbars, n+1 busbars are required for this low-inductance busbar system, with the outer busbars being directly connected to one another in an electrically conductive manner. With this low-inductance busbar system, the capacitors of the relief networks cannot be attached to the busbars of the busbar system with little dispersion. In addition, this constructed phase module requires a relatively large volume.

A low-induction capacitor battery is known from the German utility model G 89 09 246.5, which consists of several capacitors attached to a support plate, whereby

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the capacitors are electrically connected in series and/or parallel. A stack of metal plates and larger plastic plates is provided as the support plate, with a plastic plate arranged between two metal plates. The plastic plates are provided with a number of holes and the metal plates with holes corresponding to the holes in the plastic plates, with the diameter of the holes in the metal plates being significantly larger than the diameter of the corresponding hole in the plastic plates. The metal plates also serve as busbars for the electrical connection of the capacitors.

In an advantageous embodiment of this capacitor battery, a double-clad circuit board is provided as the support plate, the smaller copper claddings of which each form at least one connection surface for the capacitors and are each electrically connected to a busbar, with electrolytic capacitors with solder pins being provided as capacitors.

From the European patent application 0 519 305 A2, a converter assembly with at least two semiconductor power modules per AC phase is known, which are detachably attached to a heat sink. This converter assembly has three phase modules, each of which has a circuit, also called a snubber circuit. A circuit network is also provided for the converter. The phase modules of the converter are electrically connected in parallel to an intermediate circuit capacitor bank. This capacitor bank consists of a busbar system and several capacitors. The busbar system is electrically and securely attached to the power connections of the semiconductor power modules using metal sleeves. The components of the circuit

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The power networks of the phase modules and the converter are connected to the busbar system above and below the concentrically arranged capacitors of the capacitor bank via the shortest possible route and thus to its associated semiconductor power module in an electrically conductive manner. The disadvantage of this converter unit is the separate construction of the low-inductive power busbar and wiring elements. Since the busbar system is mainly pressed in the areas of the components of the wiring networks and the capacitors of the capacitor bank, there are many areas in the busbar system in which air is trapped, which means that the high-voltage properties are not very good. In addition, the assembly effort is still complex due to the screw connections of the components and the capacitors.

The invention is based on the object of specifying a low-inductance, high-voltage-insulated connection between power semiconductors with additional connection of circuit components, for example capacitors, diodes, resistors.

This object is achieved according to the invention by the features of the characterizing part of claim 1.

Because a multilayer circuit board with several current-carrying layers is provided as the basis for the low-inductive high-current busbar, the circuit elements of the relief network(s) can be electrically connected to one another using copper-clad conductor tracks on one side, for example the soldering side of the high-current busbar. This means that the circuit elements are connected to the connections of the power semiconductors with little stray current. This high-current busbar can be used as

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other circuit boards are automatically assembled and wave soldered.

The individual electrically conductive layers, each of which forms a power connection, are pressed together under high pressure without partial discharge using circuit board base material as an insulating layer. The high-current busbar therefore has minimal or no air inclusions, which means that this high-current busbar has good to very good high-voltage properties.

Depending on the application, the control circuits of the power semiconductors can be integrated into the high-current busbar.
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Further advantageous embodiments can be found in claims 2 to 6.

To further explain the invention, reference is made to drawing 0, in which an embodiment of the low-inductive, multi-layer high-current busbar according to the invention in printed circuit board technology for power converter modules is schematically illustrated.

Figure 1 · shows an equivalent circuit diagram of an inverter phase, whereas the

Figure 2 shows the corresponding spatial structure as a side view, the

Figure 3 shows a section of the structure according to Figure 2,

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Figure 4 shows an equivalent circuit diagram of a three-phase inverter and the

Figure 5 shows a view of the component side of a high-current busbar according to the invention for a three-phase inverter according to Figure 4.

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The equivalent circuit diagram shown in Figure 1 shows the schematic structure of an inverter phase 2, consisting of two branch pairs 4 and 6 connected electrically in parallel and two relief networks 8 and 10. Each branch pair 4 or 6 is assigned a relief network 8 or 10, whereby these relief networks 8 and 10 are also referred to as RCD voltage limiters for branch pairs. According to the article "IGBT modules in power converters: regulating, controlling, protecting", printed in the German magazine "etz", Volume 110, 1989, Issue 10, pages 464 to 471, RCD voltage limiters for branch pairs are used for power converters with higher output current because they enable shorter line lengths in the wiring network. Each branch pair 4 or 6 contains two power semiconductors Tl,T2 or Tl',T2'. By using two branch pairs 4 and 6 connected electrically in parallel, the value of a phase current reaches approximately twice the current carrying capacity of a power semiconductor Tl or T2 or Tl ¹ or T2 ' of a branch pair 4 or 6. The power semiconductors Tl and Tl ¹ are electrically connected to the power terminals P and L and the power semiconductors T2 and T2' are electrically connected to the power terminals L and N. An intermediate circuit of a converter is connected to the power terminals P and N, with a load or a phase of a load being connected to the power terminal L. These power terminals P, L and N are shown in a thicker wire gauge than the electrical lines of the relief networks 8 and 10.

In the equivalent circuit diagram, T1, T1', T2 and T2' are shown as power semiconductors as insulated gate bipolar transistors (IGBT). Self-blocking field effect transistors (MOS-FET) or power transistors (LTR) can also be used without changing the circuit of this inverter phase or the relief networks 8 and 10

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The power semiconductors Tl,..., T2 ' are turn-off power semiconductors. A gate turn-off (GTO) thyristor can also be used as a turn-off power semiconductor, although the associated relief network may then be more complex.

Figure 2 shows a side view of an inverter phase 2 according to the equivalent circuit diagram in Figure 1. This inverter phase 2 consists of a heat sink 12, the power semiconductors T1, T1', T2 and T2' and a populated inventive low-inductance, multi-layer high-current busbar 14. The components of this high-current busbar 14 are capacitors C1,...,C8, diodes D1,...,D4 and resistors R1,...,R6 of the two relief networks 8 and 10 for the branch pairs 4 and 6 of the inverter phase 2.

This multi-layer high-current busbar 14 consists of several electrically conductive layers 16, 18 and 20 and several insulating layers 22, 24, 26 and 28. The electrically conductive layers 16, 18 and 20 are pressed together without partial discharge using these insulating layers 22 and 24, which are each arranged between two adjacent electrically conductive layers 16 and 18 or 18 and 20. Circuit board base material can be used as insulating layer 22 and 24. Copper layers or copper sheets are used as electrically conductive layers 16, 18 and 20. These conductive layers 16, 18 and 20 serve as power connections P, L and N of the inverter phase 2. These power connections P, L and N are shown in the equivalent circuit diagram according to Figure 1 with a thicker line width to show that an electrically conductive layer 16, 18 and 20 is provided for each of these power connections P, L and N.

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The flat side 30 of the electrically conductive layer 16 of the high-current busbar 14, which faces the components of the two relief networks 8 and 10, also has an insulating layer 26, so that there is sufficient air and creepage distance between the connection pins of the components and the electrically conductive layer (power connection P). In addition, the flat side 32 of the electrically conductive layer 20 of the high-current busbar 14, which faces away from the components of the two relief networks 8 and 10, also has an insulating layer 28 in order to ensure a sufficient air and creepage distance between the connection pins of the components of the two relief networks 8 and 10 and the electrically conductive layer 20 (power connection N). The side of the insulating layer 26 of the high-current busbar 14 facing the components Rl,...,R6,C1,...,C8 and Dl,...,D4 is also referred to as the component side, which as usual has a printed image from which it can be seen where which component of the relief networks 8 and 10 must be placed. The side of the insulating layer 28 of the high-current busbar 14 facing away from the components Rl,...,R6,C1,...,C8 and Dl,...,D4 is referred to as the soldering side, which is provided with copper-clad conductor tracks 34 (Figure 3) with which the components of the relief networks 8 and 10 are electrically connected in accordance with the equivalent circuit diagram in Figure 1. So that the components of the relief networks 8 and 10 can be soldered on the component side of the high-current busbar 14 in accordance with the equivalent circuit diagram in Figure 1, in particular on the soldering side, the multi-layer high-current busbar 14 is provided with numerous through-holes.

Figure 3 shows a section of the high-current busbar 14 according to the invention, in which a contact, for example the contact of one of the two power semiconductors Tl,T2 or Tl ¹ ,T2 ¹ of the branch pair 4 or 6 with the

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Power connection L or the electrically conductive layer 18 is shown in more detail. This detail view shows that an electrically conductive layer 18 is electrically connected to a main connection (collector, emitter) of a power semiconductor T1, T2, T1' or T2' by means of a sleeve 36 made of electrically conductive material, for example a copper sleeve, and a screw 38. The conductor tracks 34 of the insulating layer 28 can also be seen in the illustration. Furthermore, in this illustration the insulating layer 26 is provided with conductor tracks 34. In the contact area, a hole in the insulating layer 22 or 24 is smaller than a hole in the electrically conductive layer 16 or 20, whereby the air and creepage distances between two adjacent electrically conductive layers 16, 18 or 18, 20, each of which has a different potential, are significantly increased. In order to ensure that no layers are damaged during the production of the multi-layer high-current busbar 14, i.e. when pressing the layers 16, 18, 20 and the insulating layers 22,..., 28, insulating pieces 40 and 42 are provided at the contact points and at the ends of the layers. The insulating pieces 40 have a circular shape, with the insulating pieces 42 being cuboid-shaped. In addition, the resulting cavities in the high-current busbar 14 are eliminated as a result of the improvement of the air and creepage distances between two electrically conductive layers 16, 18 and 18, 20 with different potentials, as a result of which this high-current busbar 14 has good to very good high-voltage properties.

Figure 4 shows an equivalent circuit diagram of a multi-phase converter module 44, for example a three-phase inverter 44. This inverter 44 is provided with three branch pairs 46, 48 and 50, each of which is assigned a relief network 52, 54, 56. These are RCD voltage limiters for branch pairs, whereby the

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Resistances of the individual RCD voltage limiters 52, 54 and 56 are concentrated by one or more resistors Rl,..., Rn at one point of the inverter 44. This makes it possible to use force-cooled resistors, which, like the power semiconductors Tl, T2 or T3, T4 or T5, T6 of the branch pair 46 or 48 or 50, are arranged externally of the high-current busbar 14. As in the equivalent circuit diagram according to Figure 1, the electrical connections, which are implemented by an electrically conductive layer 16, 18 or 20 of the high-current busbar 14, are shown here by a thicker line.

Figure 5 shows a view of the component side of the high-current busbar 14 of the three-phase inverter 44 according to the equivalent circuit diagram in Figure 4. On this component side, the individual fields are marked where the components of the relief networks 52, 54 and 56 are to be placed. Due to the power loss of the diodes Vl to V6, these are each provided with a circuit board heat sink 60. Depending on the application, the control units of the power semiconductors Tl,...,T6 can also be integrated on the multi-layer high-current busbar 14. The connection areas, which are marked with P, N and the load connections R, S and T, show sections of the correspondingly designated electrically conductive layers 16, 20 and 18, 18' and 18'', which are arranged one above the other. Screws 38 are passed through the holes in these contact areas, each of which is provided with a copper sleeve 36, which, however, is not shown.

By means of this multi-layer high-current busbar 14 according to the invention for high voltages, for example 700 V to 1.5 kV, the components of the relief networks 8, 10 or 52, 54 and 56 can be connected with low dispersion to the connections of the power semiconductors Tl, T2, Tl'T2' or Tl, T2,..., T5, T6 of the branch pairs 4, 6 or

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46,48 and 50 of the inverter phase 2 or the three-phase inverter 44. In addition, the high-current busbar 14 has very low inductance and has good to very good high-voltage properties.

Claims (6)

3067 · Protection claims 1. Single-phase or multi-phase converter module (2 or 44), consisting of at least one branch pair (4,6 or 46,48,50) with two power semiconductors (Tl,Tl', T2,T2' or Tl,T2;...;T5,T6) each arranged between two power connections (P,L or L,N), each branch pair (4,6 or 46,48,50) being assigned a relief network (8,10 or 52,54,56) consisting of capacitors (C1,C2;C3,C4; C5,C6;C7,C8 or Cl,...,C4;...;C9,...C12), diodes (D1,D2;D3,D4 or Vl,V2;...;V5,V6) and resistors (Rl,...,R3;R4,...,R6 or Rl,...,Rn), characterized in that these power semiconductors (Tl,Tl';T2,T2' or Tl,T2;...;T5,T6) and the components of the associated relief networks (8,10 or 52,54,56) are electrically connected to one another by means of a low-inductance, multi-layer high-current busbar (14) for high voltages in printed circuit board technology, with an electrically conductive layer (16,18,20) being provided for the power connections (P,L,N) and conductor tracks (34) being provided for the electrical connections of the components of the relief networks (8,10 or 52,54,56), with these conductive layers (16,18,20) and the conductor tracks (34) being insulated from one another are. 2. Single-phase or multi-phase converter module (2 or 44) according to claim 1, characterized in that a flat side (30) of an electrically conductive layer (16) of the low-inductance high-current busbar (14), which faces the components of the relief networks (8, 10 or 52, 54, 56), is provided with an insulating layer (26). 3067 · 3. Single-phase or multi-phase converter module (2 or 44) according to claim 1, characterized in that the insulating layers (22, 24, 26, 28) and the conductive layers (16, 18, 20) of the low-inductance high-current busbar (14) are pressed together without partial discharge. 4. Single-phase or multi-phase power converter module (2 or 44) according to claim 1, characterized in that the components of the relief networks (8, 10 or 52, 54, 56) are electrically connected by means of through-contacts to the electrically conductive layers (16, 18, 29) and the conductor tracks (34) on the side of the low-inductance high-current busbar (14) facing away from the components. 5. Single-phase or multi-phase power converter module (2 or 44) according to claim 1, characterized in that circuit board base material is provided as the insulating layer (22, 24, 26, 28). 6. Single-phase or multi-phase power converter module (2 or 44) according to claim 1, characterized in that the electrically conductive layers (16, 18, 20) consist of copper. ·