Voltage-Regulated Power Converter Module

Abstract

A voltage-regulated power converter module includes an electrical charge storage device and a semiconductor switch connected thereto and having a collector, a gate and an emitter, in which the collector-emitter path of the semiconductor switch is switched into a current path between first and second alternating-current terminals of the power converter module. The alternating-current terminals can be interconnected through a bypass switch. The voltage-regulated power converter module is intended to minimize the occurrence of damage in the event of a fault, and allow the multilevel power converter to continue operating without possibly having to use an extremely fast bypass switch for this purpose. To this end, the collector and the gate of the semiconductor switch are interconnected through a circuit configuration, which is configured in such a way that it becomes conductive above a predefined voltage threshold. A power converter is also provided.

Claims

1-13. (canceled)

14. A voltage-regulated power converter module, comprising: first and second alternating-current terminals defining a current path therebetween; a bypass switch configured to interconnect said alternating-current terminals; an electrical charge storage device; a semiconductor switch connected to said electrical charge storage device, said semiconductor switch including a collector, a gate, an emitter and a collector-emitter path switched into said current path between said first and second alternating-current terminals; and a circuit configuration interconnecting said collector and said gate of said semiconductor switch, said circuit configuration being configured to become conductive above a predefined voltage threshold.

15. The voltage-regulated power converter module according to claim 14, wherein the voltage-regulated power converter module is a half-bridge module.

16. The voltage-regulated power converter module according to claim 14, wherein: the voltage-regulated power converter module is a full-bridge module or a clamp double sub module; said semiconductor switch is one of a plurality of semiconductor switches of said full-bridge module or said clamp double sub module; each of said semiconductor switches has a collector, a gate, an emitter and a collector-emitter path switched into said current path; said circuit configuration is one of a plurality of circuit configurations configured to become conductive above a predefined voltage threshold; and each of said circuit configurations interconnects said collector and said gate of a respective one of said semiconductor switches.

17. The voltage-regulated power converter module according to claim 14, wherein: said semiconductor switch is one of a plurality of semiconductor switches each having a collector and a gate; said circuit configuration is one of a plurality of circuit configurations configured to become conductive above a predefined voltage threshold; and each of said circuit configurations interconnects said collector and said gate of a respective one of said semiconductor switches.

18. The voltage-regulated power converter module according to claim 14, wherein said circuit configuration includes a suppressor diode or a suppressor diode chain.

19. The voltage-regulated power converter module according to claim 14, wherein said circuit configuration is a suppressor diode or a suppressor diode chain.

20. The voltage-regulated power converter module according to claim 14, wherein said electrical charge storage device is a capacitor.

21. The voltage-regulated power converter module according to claim 14, wherein said semiconductor switch is a transistor.

22. The voltage-regulated power converter module according to claim 21, wherein said transistor is a bipolar transistor including an insulated gate electrode.

23. The voltage-regulated power converter module according to claim 14, wherein said bypass switch is a mechanical switch.

24. The voltage-regulated power converter module according to claim 14, which further comprises a control unit for said bypass switch, said control unit being configured to close said bypass switch upon detection of a malfunction of said semiconductor switch.

25. The voltage-regulated power converter module according to claim 14, wherein the voltage-regulated power converter module is constructed for at least one of a nominal voltage of more than 800 V or a nominal current of more than 500 A.

26. A power converter, comprising: a plurality of voltage-regulated power converter modules according to claim 14 each having respective alternating-current terminals; said voltage-regulated power converter modules being series-connected at said alternating-current terminals.

Description

[0026] Exemplary embodiments of the invention are described in greater detail on the basis of drawings. In the drawings:

[0027] FIG. 1 shows a schematic circuit diagram of a half-bridge VSC module comprising a suppressor diode chain at only one IGBT,

[0028] FIG. 2 shows a schematic circuit diagram of a half-bridge VSC module comprising a suppressor diode chain at both IGBTs,

[0029] FIG. 3 shows a schematic circuit diagram of a full-bridge VSC module comprising a suppressor diode chain at four IGBTs,

[0030] FIG. 4 shows a schematic circuit diagram of a multilevel power converter, and

[0031] FIG. 5 shows a schematic circuit diagram of a clamp double sub-VSC-module comprising a suppressor diode chain at four IGBTs.

[0032] Identical parts are provided with the same reference numbers in all figures.

[0033] FIG. 1 shows the circuit diagram of a first exemplary embodiment of a voltage-regulated power converter module 1 in a half-bridge circuit which is comparatively simply designed but is limited in terms of its switching possibilities. The power converter module 1 includes two external alternating-current terminals 2, 4, to which multiple power converter modules 1 are connected in series, as described in greater detail with reference to FIG. 4. In the exemplary embodiment, the power converter module 1 comprises two semiconductor switches 6, 8 in the form of normal-conducting bipolar transistors including an insulated gate electrode (an insulated-gate bipolar transistor (IGBT)), to which a freewheeling diode 10, 12, respectively, is connected contradirectionally in parallel. Other types of transistors can also be used, however, in principle.

[0034] In FIG. 1 and in the subsequent drawings, the semiconductor switches 6, 8 are each represented only as individual IGBTs. It goes without saying that this can also be merely representative for multiple IGBTs which form one functional unit, i.e., which are connected in parallel, for example, and the gates of which are connected to each other or are jointly activated.

[0035] The semiconductor switches 6, 8 are interconnected with a charge storage means 14 in the form of a capacitor as a central element, in the manner of a half-bridge, i.e., the two semiconductor switches 6, 8 are series-connected in the same direction and, together with the charge storage means 14, form a circuit. The semiconductor switches 6, 8 each comprise a collector 6k, 8k, respectively, a gate 6g, 8g, respectively, and an emitter 6e, 8e, respectively. The first alternating-current terminal 2 is connected to the connection between the emitter 6e of the first semiconductor switch 6 and the collector 8k of the second semiconductor switch 8 of the circuit. The second alternating-current terminal 4 is connected to the connection between the emitter 8e of the second semiconductor switch and the charge storage means 14. The semiconductor switch 8 is therefore connected, via its collector-emitter path, into the current path 16 between the two alternating-current terminals 2, 4.

[0036] The semiconductor switches 6, 8 can be activated/switched individually by means of an electronic driver 18. The electronic driver is represented in FIG. 1 only for semiconductor switch 8, for reasons of clarity; the semiconductor switch 6 comprises a similar driver. The driver is capable of switching the connected IGBT on or off with the aid of external control pulses. In one embodiment, a structurally implemented interlock can be provided, which prevents the two semiconductors 6, 8 from switching simultaneously. As a result, the voltage U present at the charge storage means 14 can be switched to the alternating-current terminals 2, 4. Therefore, depending on the switching state of the semiconductor switches 2, 4, the voltage +U or 0 V is present between the alternating-current terminals 2, 4. Any current direction is possible in this case. Due to the series connection of multiple power converter modules 1, a stepped voltage profile can be generated, as is described with reference to FIG. 4.

[0037] In the event of a fault of one of the semiconductor switches 6, 8, in particular of the semiconductor switch 8 in this case, an overcharging of the charge storage means 14 can result. The control electronics must detect this rapidly and close a bypass switch 20 which connects the two alternating-current terminals 2, 4. As a result, the power converter module 1 is bridged and the system can continue operating until the next servicing. The bridging must take place very rapidly, however.

[0038] In order to ensure that slower mechanical bypass switches 20 can be utilized nevertheless, the collector 8k of the semiconductor switch 8 is connected to the gate 8g via a circuit arrangement 22 which consists of a series of suppressor diodes 24. Therefore, if the voltage between the collector 8k and the gate 8g becomes too great due to the non-activation of the semiconductor switch 8, the suppressor diodes 24 break down and the gate 8g is connected to the voltage at the collector 8g. As a result, a current flow through the semiconductor switch 8 is established, which possibly results in destruction of the semiconductor switch 8 and the suppressor diodes 24, but temporarily prevents destruction of the charge storage means 14 until the bypass switch 20 has been closed. The charge storage means 14 therefore remains intact.

[0039] The above-described driver 26 of the semiconductor switch 6 is also represented in a second embodiment of a voltage-regulated power converter module 1 according to FIG. 2, which is described only on the basis of the differences from FIG. 1. In the case of the semiconductor switch 6 as well, the collector 6k is additionally connected to the gate 6g via an identical circuit arrangement 28 which consists of a series of suppressor diodes 30.

[0040] FIG. 3 shows yet another exemplary embodiment, specifically the circuit diagram of a power converter module 1 in a full-bridge circuit. In this case as well, the power converter module comprises two alternating-current terminals 2, 4, but four semiconductor switches 6, 8, 32, 34, to each of which, in turn, a freewheeling diode 10, 12, 36, 38, respectively, is connected in parallel for the purpose of protection against an overvoltage during switching-off. The semiconductor switches 32, 34 are designed identically to the semiconductor switches 6, 8 as shown in FIGS. 1 and 2.

[0041] The semiconductor switches 6, 8, 32, 34 are interconnected with the capacitor 14 as a central element in the manner of a full bridge, i.e., two semiconductor switches 6, 8 and two semiconductor switches 32, 34 series-connected in the same directionbetween which one of the alternating-current terminals 2 or 4, respectively, is situatedare connected to each other and to the capacitor 14 in parallel in the same direction. Therefore, depending on the switching state of the semiconductor switches 6, 8, 32, 34, either +U, U or 0 V is present between the alternating-current terminals 2, 4. Any current direction is possible in this case.

[0042] In the exemplary embodiment in FIG. 3 as well, a bypass switch 20 is provided between the alternating-current terminals 2, 4; the drivers of the semiconductor switches 6, 8, 32, 34 are not represented. In each semiconductor switch 6, 8, 32, 34, the particular collector 6k, 8k, 32k, 34k is connected via an identical circuit arrangement 22, 28, 40, 42 to the particular gate 6g, 8g, 32g, 34g, respectively, each circuit arrangement consisting of a series of suppressor diodes 24, 30, 44, 46.

[0043] In the embodiment in FIG. 3, two possible current paths 16, 48 result between the two alternating-current terminals 2, 4. In one alternative embodiment (not shown), it is also possible that only the semiconductors 6, 32 or 8, 34 of a current path 48 or 16, respectively, are provided with the circuit arrangements 28, 40 or 22, 42, respectively.

[0044] FIG. 4 shows a schematic representation of an exemplary embodiment of a power converter 50. The power converter 50 comprises six power semiconductor valves 52 which are connected to each other in a bridge circuit. Each of the power semiconductor valves 52 extends between one of the three three-phase current terminals 54, 56, 58 and one of the two direct-current terminals 60, 62.

[0045] A three-phase current terminal 54, 56, 58 is provided for each phase of the alternating-voltage network. In the exemplary embodiment shown, the alternating-voltage network is three-phase. The power converter 50 therefore also comprises three three-phase terminals 54, 56, 58. In the exemplary embodiment shown, the power converter 50 is part of a high-voltage direct-current power transmission system and is used for connecting alternating-voltage networks in order to transmit high electrical powers between these networks. It is mentioned at this point, however, that the power converter 50 can also be part of a so-called FACTS system which is utilized for network stabilization or ensuring a desired voltage quality. A use of the power converter 50 in the drive technology is also possible.

[0046] Each of the power semiconductor valves 52 in FIG. 4 is identically designed and comprises a series circuit including power converter modules 1 and an inductor 64. The power converter modules 1 are designed according to one of the exemplary embodiments described with reference to one of FIG. 1 to FIG. 3, or according to the exemplary embodiment which is described in the following with reference to FIG. 5.

[0047] The embodiment of a power converter module 1 represented in FIG. 5 is designed as a so-called clamp double submodule. It is described with reference to the differences from the embodiment according to FIG. 3.

[0048] In the clamp double sub module, the central arrangement and interconnection of the charge storage means 14 from FIG. 3 is essentially changed: In the exemplary embodiment in FIG. 3, i.e., a full-bridge module, the charge storage means 14 is switched into a connecting line between the current path 16 and the current path 48. In the clamp double sub module according to FIG. 5, two separate charge storage means 14a, 14b are initially provided, each of which is switched, in parallel, into a separate connecting line between the current path 16 and the current path 48. A potential isolating diode 66 and a limiting resistor 68 are situated in the current path 16 between the two aforementioned connecting lines comprising the charge storage means 14a, 14b. The current path 48 likewise comprises a potential isolating diode 70 and a limiting resistor 72.

[0049] The current path 16 is connected to the current path 48 via a circuit branch 74, in which a further semiconductor switch 76 is situated. This semiconductor switch, as is also the case with the remaining semiconductor switches 76, is designed as an IGBT comprising a corresponding collector 76k, a gate 76g, and an emitter 76e, and connected thereto, contradirectionally in parallel, is a freewheeling diode 78. The driver of the semiconductor switch 76 is not represented, for reasons of clarity.

[0050] The circuit branch 74 connects the cathode side of the potential isolating diode 66 to the anode side of the potential isolating diode 70, wherein the limiting resistor 72 situated between the aforementioned anode and the circuit branch 74 was overlooked.

[0051] Due to the additional semiconductor 76 in the circuit branch 74 and the resultant additional current paths, the voltage-regulated power converter module 1 according to FIG. 5 allows for a plurality of voltage states at its output terminals, which can be utilizedin particular during fault scenarios of the overall power converterin order to make it easier to control these fault scenarios. The central, above-described semiconductor switch 76 is not provided with an above-described circuit arrangement, since, in the event of the failure thereof, a discharge of the charge storage means 14a, 14b can also be ensured by means of the remaining semiconductor switches 6, 8, 32, 34. To this end, in a manner similar to that represented in FIG. 3, in each semiconductor switch 6, 8, 32, 34, the particular collector 6k, 8k, 32k, 34k is connected via an identical circuit arrangement 22, 28, 40, 42 to the particular gate 6g, 8g, 32g, 34g, respectively, each of which consists of a series of suppressor diodes 24, 30, 44, 46.

LIST OF REFERENCE NUMBERS

[0052] 1 voltage-regulated power converter module [0053] 2, 4 alternating-current terminal [0054] 6, 8 semiconductor switch [0055] 6e, 8e emitter [0056] 6g, 8g gate [0057] 6k, 8k collector [0058] 10, 12 freewheeling diode [0059] 14, [0060] 14a, 14b charge storage means [0061] 16 current path [0062] 18 driver [0063] 20 bypass switch [0064] 22 circuit arrangement [0065] 24 suppressor diode [0066] 26 driver [0067] 28 circuit arrangement [0068] 30 suppressor diode [0069] 32, 34 semiconductor switch [0070] 32e, 34e emitter [0071] 32g, 34g gate [0072] 32k, 34k collector [0073] 36, 38 freewheeling diode [0074] 40, 42 circuit arrangement [0075] 44, 46 suppressor diode [0076] 48 current path [0077] 50 power converter [0078] 52 power semiconductor valve [0079] 54, 56, 58 three-phase current terminal [0080] 60, 62 direct-current terminal [0081] 64 inductor [0082] 66 potential isolating diode [0083] 68 limiting resistor [0084] 70 potential isolating diode [0085] 72 limiting resistor [0086] 74 circuit branch [0087] 76 semiconductor switch [0088] 76e emitter [0089] 76g gate [0090] 76k collector [0091] 78 freewheeling diode