DE212016000300U1 - Capacitor with integrated short-circuiting device, in particular for two-pole sub-modules of a multi-stage converter, and a multi-phase multi-stage converter with such a capacitor - Google Patents

Abstract

Capacitor (1020) for bipolar sub-modules (610) of a multi-stage converter (3), comprising a winding (1021) formed from electrically conductive first films and at least one intermediate electrically insulating second film, having terminals (1023, 1024), which are connected to the two electrically conductive films, and with an electrically insulating separating material (1027) which is arranged between the two mutually facing terminals (1023, 1024), characterized in that the separating material (1027) has a melting temperature at which it liquefies that a short-circuiter (1022) is present, which has a short-circuit element (1025) which a) in the region of the two terminals (1023, 1024) is arranged, b) to which one terminal (1024) is electrically connected, c ) is held in a first position by the solid release material (1027) and d) is acted upon by a force which causes the short-circuiter (1022) to melt when the release material (1 027) moves to a second position, in which the short-circuiter (1022) at least also contacts the other terminal (1023) and thereby establishes an electrical short circuit between the two terminals (1023, 1024).

Description

The invention relates to a capacitor with integrated short-circuiter, in particular for two-pole sub-modules of a multi-stage converter, as well as a multi-stage converter with such a capacitor according to the preamble of claim 1 and of claim 9.

Multi-phase modular multi-stage converters are known and have a plurality of phase modules, each formed of a plurality of electrically connected in series bipolar sub-modules. The sub-modules in turn each have a power module with a plurality of semiconductor switches and a capacitor as an energy storage, to each of which a DC link voltage is applied.

The capacitors are designed as film capacitors, which are very robust against damage due to their self-healing property. Therefore, film capacitors are popular in modular multi-stage converters for buffering sub-module voltages. With the large number of built-in capacitors with very high energy content, however, it can lead to insulation errors, although not necessarily disturbing the converter operation, but due to a strong heat generation can lead to smoke, connected to destructive flashovers within the inverter.

The disadvantage here is that the heat generation and smoke formation delayed by infrared sensors and smoke detectors and thus usually detected too late.

Therefore, e.g. Used overpressure switch, which recognize the strong heating by the expansion of the filling material (gas or resin). The disadvantage of this solution is that additional signal processing and coordination is required, which can hardly be retrofitted and has additional sources of error.

In any of these solutions to the problem, however, the inverter is shut down unexpectedly, which can result in significant costs.

The object of the invention is to short-circuit the film capacitor in the event of a strong evolution of heat within a film capacitor, before smoke is formed.

The object is solved by the features of claim 1; the dependent claims represent advantageous embodiments.

With regard to the condenser, the solution provides that the separating material has a melting temperature at which it liquefies, that there is a short-circuiting element which has a short-circuit element which a) is arranged in the region of the two connections, b) with the one connection c) is held by the solid release material in a first position and d) is acted upon by a force that moves the short-circuited in molten release material in a second position in which the short-circuited contacts at least the other terminal and thereby an electrical Short circuit between the two connections manufactures.

A technically simple solution is obtained when the force acting on the short-circuiter is gravity and the short-circuiter is held in the first position relative to the direction of gravity above the pads by the solid release material.

To facilitate the movement to the second position, it is proposed that the short-circuiter has a wedge shape whose wedge tip points downwards with respect to the direction of gravity.

A further solution is obtained when the force acting on the short-circuiting force is the force of a spring connected to the one terminal, which is arranged in the clamped state in the solid separating material and relaxes in the molten separating material while increasing its volume.

A simple embodiment provides that the spring is a helical spring which increases its longitudinal extent in the molten separating material and thereby moves the short-circuiting device against the other terminal until it comes into contact with the other terminal by contacting the other terminal and thus establishing an electrical connection.

Appropriately, mutually facing connecting surfaces are formed at the two terminals, between which the separating material is arranged.

Advantageously, a housing is provided, in which the winding is arranged and guided by the at least one of the two connections to the outside.

The production is simplified if the release material is a potting compound.

With regard to the multi-stage converter, the solution provides that the separating material has a melting temperature at which it liquefies, and that a short-circuiting device a) is arranged in the region of the two connections, b) to which one connection is electrically connected, c) from solid release material is held in a first position and d) is acted upon by a force that moves the short-circuited with molten separating material in a second position in which the short-circuited contacts at least the other terminal and thereby produces an electrical short circuit between the two terminals.

• 1 eine Anordnung 1 mit einem modularen Mehrstufenumrichter,
• 2 einen Mehrstufenumrichter mit drei Phasenmodulen,
• 3 einen Mehrstufenumrichter mit sechs Phasenmodulen,
• 6 das Phasenmodul gemäß 2 und 3 mit Sub-Modulen,
• 7 ein Sub-Modul,
• 8 eine Leistungshalbleiterschaltung als Vollbrückenschaltung,
• 9 eine Leistungshalbleiterschaltung als Halbbrückenschaltung,
• 10 eine erste Ausführung des Kondensators mit integriertem Kurzschließer und
• 11 eine zweite Ausführung des Kondensators mit integriertem Kurzschließer.

The invention will be described in more detail with reference to an embodiment. Show it:

• 1 an arrangement 1 with a modular multi-stage converter,
• 2 a multi-stage converter with three phase modules,
• 3 a multi-stage converter with six phase modules,
• 6 the phase module according to 2 and 3 with sub-modules,
• 7 a sub-module,
• 8th a power semiconductor circuit as a full bridge circuit,
• 9 a power semiconductor circuit as a half-bridge circuit,
• 10 a first embodiment of the capacitor with integrated short-circuiter and
• 11 a second embodiment of the capacitor with integrated short-circuiter.

In 1 is an arrangement 1 with a modular multi-stage converter 3 (modular multi-level inverter). The modular multi-stage converter 3 is three-phase via a connecting rail 5 and a transformer 5a with a power supply network 7 electrically connected. The power supply network 7 is a three-phase AC power supply network in the embodiment 7 , By means of a current sensor 210 is the through the inverter 3 flowing current measured. Current readings 13 become a drive unit 15 the modular multistage converter 3 transfer. Furthermore, by means of a voltage sensor eighteen (which is designed here as a transducer) on the connection rail 5 applied voltage measured. This voltage is substantially the same as that of the modular multi-stage converter 3 applied voltage. The voltage readings of the terminal voltage 21 become the drive unit 15 transfer.

Based on preset setpoints 25 (Active power or reactive power setpoints) is calculated by the control unit 15 control signals 28 leading to the modular multi-stage converter 3 be transmitted. By means of these drive signals 28 becomes the multistage converter 3 so controlled that on the connecting rail 5 set the desired current and voltage values. The drive unit 15 controls in this way the multi-stage converter 3 ,

In 2 is an embodiment of a multi-stage converter 3 represented, which three phase modules 210 having. The three phase modules 210 are connected in delta connection and with three phases L1 . L2 and L3 of the power supply network 7 connected. The structure of the phase modules 210 is in 6 shown.

In 3 is an embodiment of a multi-stage converter 3 shown which six phase modules 210 having. These six phase modules 210 are arranged in a bridge circuit (here: in a B6 bridge circuit). In this case, in each case one terminal of a first phase module and one terminal of a second phase module are electrically connected to one another and form an AC voltage terminal 302 . 304 or 306 ,

The other terminal of the first phase module is with a positive DC voltage connection 310 and the other terminal of the second phase module is with a negative DC voltage terminal 312 connected. The three AC voltage connections 302 . 304 and 306 are at the three stages L1 . L2 and L3 of the AC power supply network 7 connected.

In 4 is an embodiment of the phase module 210 shown in more detail. The phase module 210 has a first connection 604 and a second port 606 on. The first connection 604 is via a current sensor 608 with a first sub-module 610 electrically connected. The first sub-module 610 is electrically connected in series with other sub-modules 610 ; Overall, the phase module has 210 n submodules 610 on. The last of the n sub-modules 610 is via a coupling inductance 612 electrically with the second connection 606 connected. By means of the current sensor 608 becomes the through the phase module 210 flowing current measured. The first connection 604 and the second connection 606 can each with a phase of the AC power supply network 7 be connected.

In 5 is an embodiment of a sub-module 610 shown in detail. The bipolar sub-module 610 has a first sub-module connection 704 and a second sub-module connector 706 on. The two sub-module connections 704 and 706 are with a power semiconductor circuit 710 connected (more specifically, with an AC voltage terminal of the power semiconductor circuit 710 ). A DC voltage terminal of the power semiconductor circuit 710 is via a DC voltage intermediate circuit 714 with an energy storage 724 in the form of a capacitor module 724a (With a capacitor 1020 ) connected. In the DC voltage intermediate circuit 714 is the DC link voltage Uzk available. The power semiconductor circuit 710 is also referred to as a "power module".

A bypass occluder 730 includes a monitoring unit 732 with a bypass switch logic that has a bypass switch 731 closes when a breakdown of the DC link voltage Uzk (and thus voltage of the capacitor 1020 ) is recognized by her.

In 6 is an embodiment of the power semiconductor circuit 710 shown. The power semiconductor circuit 710 has four power semiconductor switches 810 on, which are switched on and off. Each of the power semiconductor switches 810 has a power semiconductor device with an antiparallel connected diode. In the embodiment of 8th the power semiconductor device is an IGBT (Insulated Gate Bipolar Transistor). However, in other embodiments, the semiconductor device may be configured differently, for example as an IGCT (Integrated Gate-Commutated Thyristor), IEGT (Injection-Enhanced Gate Transistor) or as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The four semiconductor switches 810 form in the embodiment of 8th a full bridge circuit. This allows the polarity of the first sub-module connection 704 and the second sub-module connector 706 applied voltage are reversed.

In 7 is another embodiment of a power semiconductor circuit 710 ' shown, which only two power semiconductor switch 810 having. The two power semiconductor switches 810 form in the embodiment of 9 a half-bridge circuit. This allows between the first sub-module connection 704 and the second sub-module connector 706 only a voltage of one polarity (or zero voltage) is output.

In 8th is the capacitor module 724a shown, this one from a capacitor 1020 and a voltage measuring device connected in parallel 1020a exists, where on the capacitor 1020 the DC link voltage Uzk is applied and buffered by this.

Is shown in 9 the capacitor 1020 , which consists of a series and parallel connection of winding 1021 each formed from wound electrically conductive (first) films in the form of metal foils and at least one intermediate electrically insulating (second) film in the form of at least one Kunstoffisolierfolie. The coils connected in series and parallel 1021 are with a short circuiter 1022 connected, designed as a heat short-circuiter and with the connections 1023 . 1024 of the capacitor 1020 connected is.

In 10 is a first embodiment of the capacitor 1020 with integrated short circuiter 1022 from the perspective of the connections of the capacitor 1020 shown schematically. It can be seen that the short-circuiter 1022 here a wedge-shaped short-circuit element 1025 that is in the area of the two terminals 1023 . 1024 arranged and by means of an equipotential bonding wire 1026 with the one connection 1024 electrically connected. The two connections 1023 . 1024 are in a solid electrically insulating release material 1027 embedded, ie the release material 1027 is thus also between the two mutually facing connection surfaces 1023 . 1024a the two connections 1023 . 1024 arranged. Here is the short-circuit element 1025 from the solid release material 1027 held in a first position, as in 10 shown. The first position is here relative to the direction 1028 gravity above the connections 1023 . 1024 and is charged by gravity.

The release material 1027 has a melting temperature selected (tuned) such that the (solid) release material 1027 melts (liquefies) when it comes due to insulation errors to a strong heat. Melts the solid release material 1027 , gravity moves the shorting element 1025 down to a second position, in which the short-circuiter 1022 also the other connection 1023 (as well as the connection 1024 directly) contacted and thereby an electrical short circuit between the two terminals 1023 . 1024 manufactures.

To facilitate the movement to the second position, it is suggested that the short-circuiter 1022 has a wedge shape, the wedge tip with respect to the direction 1028 showing gravity down.

Due to the short circuit and thus the breakdown of the capacitor voltage, the existing bypass switch logic in the affected sub-module (eg 610 ), which subsequently leads to a safe faulty declaration.

11 shows a second embodiment of the capacitor 1020 with integrated short circuiter 1022 in a schematic representation. In contrast to the first embodiment, this is cuboid short-circuit element 1025 between the two connections 1023 . 1024 and the shorting element 1025 acting force is the force of a compression spring 1029 , in the tensioned state in the solid separating material 1027 arranged and electrically connected to the terminal 1024 directly connected. In the molten separating material 1027 the spring relaxes 1029 increasing its volume or its length until the short-circuit element 1025 the other opposite terminal 1023 contacted and thereby as in the first embodiment, an electrical short circuit between the two terminals 1023 . 1024 manufactures.

Claims (9)

Capacitor (1020) for bipolar sub-modules (610) of a multi-stage converter (3), comprising a winding (1021) formed from electrically conductive first films and at least one intermediate electrically insulating second film, having terminals (1023, 1024), which are connected to the two electrically conductive foils, and with an electrically insulating separating material (1027) which is arranged between the two mutually facing terminals (1023, 1024), characterized in that the separating material (1027) has a melting temperature at which it liquefies that a short-circuiter (1022) is present, which has a short-circuit element (1025) which a) in the region of the two terminals (1023, 1024) is arranged, b) to which one terminal (1024) is electrically connected, c) is held by the solid release material (1027) in a first position and d) is acted upon by a force, which the short-circuiter (1022) with molten Trennmater Moves ial (1027) in a second position in which the short-circuiter (1022) at least also the other terminal (1023) contacted and thereby establishes an electrical short circuit between the two terminals (1023, 1024). Capacitor after Claim 1 characterized in that the force acting on the short-circuiter (1022) is gravity and the short-circuiter (1022) is in the first position with respect to the direction (1028) of gravity above the pads (1023a, 1024a) of the solid release material (1027) is held. Capacitor after Claim 2 characterized in that the short-circuiter (1022) has a wedge shape whose wedge tip points downwards with respect to the direction (1028) of gravity. Capacitor after Claim 1 , characterized in that the force acting on the short-circuiter (1022) is the force of a spring (1029), which in the tensioned state is arranged in the solid separating material (1027) and relaxes in the molten separating material (1027) while increasing its volume. Capacitor after Claim 4 characterized in that the spring (1029) is a helical spring which increases its longitudinal extent in the molten separating material (1027) and thereby moves the short-circuiter (1022) against the other terminal (1023) until it makes contact with the other terminal (1023). and thereby establishing an electrical connection at the other terminal (1023) comes to rest. Capacitor according to one of the Claims 1 - 5 , characterized in that at the two terminals (1023, 1024) facing each other connecting surfaces (1023a, 1024a) are formed, between which the separating material (1027) is arranged. Capacitor according to one of the Claims 1 - 6 , characterized by a housing in which the winding (1021) is arranged and guided by the at least one of the two terminals (1023, 1024) to the outside. Capacitor according to one of the Claims 1 - 7 , characterized in that the release material (1027) is a potting compound. A multi-phase multi-stage converter (3) having a plurality of phase modules (210) each formed of a plurality of electrically coupled bipolar modules (610) each having a plurality of semiconductor switches (710, 710 ') and a capacitor (1020) each Energy store (724), which is formed as a film capacitor, which comprises - a winding (1021), which is formed from electrically conductive first films and at least one intermediate electrically insulating second film, - terminals (1023, 1024), with the two electrically conductive first foils are connected, and - an electrically insulating separating material (1027) which is arranged between the two facing terminals (1023, 1024), characterized in that the separating material (1027) has a melting temperature at which it liquefies in that a short-circuiter (1022) a) is arranged in the region of the two terminals (1023, 1024), b) to which one terminal (1024) is electrically connected, c) is held in a first position by the solid separator material (1027), and d) is acted upon by a force that moves the short-circuiter (1022) to a second position with molten separator material (1027) in which the short-circuiter (1022) contacts the other terminal (1023) and thereby establishes an electrical short circuit between the two terminals (1023, 1024).

Images