Converter submodule with short-circuit device and power converter having same

• US 9,806,599 B2
• Filed: 06/15/2016
• Issued: 10/31/2017
• Est. Priority Date: 06/15/2015
• Status: Active Grant

• Current Assignee: GE Energy Power Conversion Technology Limited (General Electric Company)
• Original Assignee: GE Energy Power Conversion Technology Limited (General Electric Company)
• Inventors: Geske, Martin, Janning, Joerg, Brueckner, Thomas, Jakob, Roland
• Primary Examiner(s): Dole, Timothy J
• Assistant Examiner(s): LABOY ANDINO, IVAN A
• Application Number:
  US15/182,746
• Publication Number:
  US 20160365787A1
• Time in Patent Office: 503 Days
• Field of Search: 363 15- 17, 363 34, 363 35, 363 37- 43, 363 50- 55, 363 5601- 5605, 363 57- 58, 363 84- 89, 363 95- 98, 363123, 363125, 363127, 363131-132, 363135-138
• CPC Class Codes: H01T 1/14 Means structurally associated with spark gap for protecting it against overload or for disconnecting it in case of failure H01T1/15, H01T1/16, H01T1/18 take precedence; emergency protective circuit arrangements for spark gap arrestors H02H7/24
• CPC Class Codes: H01T 15/00 Circuits specially adapted for spark gaps, e.g. ignition circuits ignition circuits for internal-combustion engines F02P; electric spark ignition for combustion apparatus F23Q; protection circuits using spark gaps H02H9/06
• CPC Class Codes: H01T 2/02 comprising a trigger electrode or an auxiliary spark gap
• CPC Class Codes: H02H 7/12 for static converters or rectifiers for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981
• CPC Class Codes: H02H 9/041 using a short-circuiting device
• CPC Class Codes: H02M 1/0085 Partially controlled bridges
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/325 with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
• CPC Class Codes: H02M 7/44 by static converters
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage

Abstract

A short-circuit device and a protection method for a submodule for a power converter are disclosed. The submodule includes a bridge circuit having at least one power semiconductor branch extending between a first and a second DC voltage node and at least one controllable power semiconductor switch disposed therein to which a freewheeling diode is connected in anti-parallel, and a capacitor connected in parallel to the bridge circuit. The short-circuit device has at least one selected of the freewheeling diodes anti-parallel to the power semiconductor switches of the bridge circuit, wherein the at least one selected freewheeling diode is manufactured in press pack design and rated such that, when a fault occurs in the submodule, the at least one selected freewheeling diode breaks down due to the fault conditions and provides a durable, stable, low-impedance short circuit path between a first and a second AC voltage connection of the submodule.

Claims

1. A submodule for a power converter, comprising:

a full bridge circuit comprising at least two power semiconductor branches connected between a first DC voltage node and a second DC voltage node, each power semiconductor branch having a controllable power semiconductor switch with a freewheeling diode connected in anti-parallel thereto;

a capacitor connected in parallel to the full bridge circuit between the first and second DC voltage nodes; and

a short circuit device comprising at least one selected of the freewheeling diodes anti-parallel to the controllable power semiconductor switches of the full bridge circuit, wherein the controllable power semiconductor switches are not manufactured in press pack design, and wherein the at least one selected freewheeling diode is manufactured in press pack design and rated such that, when a fault occurs in the submodule, the at least one selected freewheeling diode breaks down due to fault conditions and provides a low-impedance short-circuit path between a first AC voltage connection and a second AC voltage connection of the submodule.

2. The submodule according to claim 1, wherein the power semiconductor branches each comprise two controllable power semiconductor switches connected in series, each controllable power semiconductor switch having an anti-parallel freewheeling diode associated thereto and the connection points thereof forming the first AC voltage connection and the second AC voltage connection of the submodule, respectively.

3. The submodule according to claim 2, wherein all of the controllable power semiconductor switches are manufactured in modular design, wherein selected freewheeling diodes are manufactured in press pack design.

4. The submodule according to claim 3, wherein the selected freewheeling diodes are exactly two freewheeling diodes, which are either positioned in a single of the two power semiconductor branches or connected to a single of the first and second DC voltage nodes.

5. The submodule according to claim 3, wherein all free-wheeling diodes are manufactured in press pack design.

6. The submodule according to claim 3, wherein the low-impedance short-circuit path comprises no further electronic components apart from the one or more selected freewheeling diodes, which are broken down, and the first and/or second diode, if present.

7. The submodule according to claim 1, wherein the bridge circuit comprises:

the first power semiconductor branch having a series connection of a first controllable power semiconductor switch and a first diode; and

the second power semiconductor branch having a series connection of a second controllable power semiconductor switch and a second diode, wherein the first and second diodes are positioned in a bridge diagonal of the bridge circuit and each controllable power semiconductor switch is assigned an anti-parallel freewheeling diode, wherein a connection point between the first controllable power semiconductor switch and the first diode forms the first AC voltage connection of the submodule and a connection point between the second controllable power semiconductor switch and the second diode forms the second AC voltage connection of the submodule.

8. The submodule according to claim 7, wherein all of the controllable power semiconductor switches, and both the first and the second diodes, are manufactured in modular design, wherein a single one of the freewheeling diodes is manufactured in press pack design.

9. The submodule according to claim 7, wherein all of the controllable power semiconductor switches, and both the first and the second diodes, are manufactured in modular design, wherein all freewheeling diodes are manufactured in press pack design.

10. The submodule according to claim 7, wherein all of the controllable power semiconductor switches are manufactured in modular design, and both the first and the second diodes and all of the freewheeling diodes are manufactured in press pack design.

11. The submodule according to claim 1, wherein the fault conditions resulting in a breakdown of the at least one selected freewheeling diode include at least one of an overvoltage over the at least one selected freewheeling diode, an overtemperature at the at least one selected freewheeling diode, and a fault current through the at least one selected freewheeling diode.

12. The submodule according to claim 11, further comprising a drive unit configured to, upon detecting a fault case, switch off all controllable power semiconductor switches of the submodule or keep them switched off to cause further charging of the capacitor up to a voltage which provides the overvoltage at the at least one selected freewheeling diode.

13. The submodule according to claim 11, comprising a triggerable spark gap connected in a branch in parallel to the full bridge circuit between the first and second DC voltage nodes, wherein the spark gap, when triggered, causes a fault current through the submodule with a reversing current which effects the breakdown of the at least one selected freewheeling diode.

14. The submodule according to claim 11, comprising a temperature influencing device configured to cause an increase of temperature at or in the vicinity of the at least one selected freewheeling diode, when a fault occurs in the submodule.

15. The submodule according to claim 14, further comprising a drive unit configured to, upon detection of a fault case, switch off all controllable power semiconductor switches of the submodule or keep them switched off and to control the temperature influencing device and/or to trigger the spark gap.

16. A power converter for converting an AC voltage into a DC voltage or vice versa, comprising:

at least one phase branch, which comprises two or more series-connected submodules according to claim 1, wherein a first AC voltage connection of at least one submodule is electrically connected to a second AC voltage connection of an adjacent submodule and wherein there is a power converter AC voltage connection tapped in each phase branch.

17. The power converter according to claim 16, further comprising:

a detection circuit configured to detect a defect of at least one controllable power semiconductor switch or its driver in any one of the submodules of the power converter; and

a control device having the drive unit configured to, upon detection of such a defect, switch off all controllable power semiconductor switches of the submodule or keep them switched off and, if needed, to take further measures resulting in the breakdown of the press pack diodes to effect the low-impedance short-circuit path in the submodule.