# US 8,570,779 B2 · Method for limiting damage to a converter having power semiconductors in the case of a short circuit in the DC voltage intermediate circuit

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- Number: US 8,570,779 B2
- Document ID: US8570779B2
- Status: Granted
- Kind: B2
- Application number: 12/531,076
- Filed: 2007-03-13
- Published: 2010-04-08
- Granted: 2013-10-29
- Earliest claimed: 2007-03-13
- Assignees: Siemens Aktiengesellschaft
- Applicants: Mike Dommaschk; Jörg Dorn; Ingo Euler; Jörg Lang; Quoc-Buu Tu; Klaus Würflinger
- Inventors: Mike Dommaschk; Jörg Dorn; Ingo Euler; Jörg Lang; Quoc-Buu Tu; Klaus Würflinger
- Web page: https://patentgrep.com/patent/US8570779B2

## CPC

- H02M 7/49: Combination of the output voltage waveforms of a plurality of converters
- H02H 7/125: for rectifiers
- H02M 1/32: Means for protecting converters other than automatic disconnection
- 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}
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)

## Abstract

A device for converting an electric current has a phase module, which in turn has an alternating current connection and at least one direct current connection connected to an intermediate direct current circuit. The device further has an energy accumulator. A phase modulation path is formed between each direct current connection and each alternating current connection. Each phase modulation path has a series connection of submodules, which each have a power semiconductor. A semiconductor protective device is provided in parallel connection to power semiconductors of each submodule. A control unit actuates the semiconductor protective device, and energy accumulator(s) are equipped for supplying energy to the control unit. The device safely prevents damage from a short circuit on the direct-current side, even when the supply grid is connected, because a direct current connection of each phase module is connected to the intermediate direct current circuit via a direct-current switch.

## Claims

### Claim 1

A method for limiting damage to a converter having power semiconductors, the converter being connected to at least one further converter or at least one machine via a DC voltage intermediate circuit affected by a short circuit, wherein a drive unit is supplied with energy by an energy store of the converter or of the DC voltage intermediate circuit, which comprises the steps of:
ascertaining, via the drive unit, a short circuit and subsequently driving at least one semiconductor protective device connected in parallel with a power semiconductor, such that a short-circuit current flows both via the semiconductor protective device and via the power semiconductor connected in parallel therewith;
charging the energy store before the converter is connected to the DC voltage intermediate circuit;
connecting the power semiconductor to the DC voltage intermediate circuit by means of a DC voltage switch;
opening the DC voltage switch before the converter is connected to a supply system;
connecting the converter to the supply system by means of AC voltage switches;
in order to connect the converter to the DC voltage intermediate circuit, first opening all the AC voltage switches and the DC voltage switch; and
afterward, in order to charge the energy stores, closing the AC voltage switches, each of the AC voltage switches is opened after charging of the energy stores, the DC voltage switch is closed for connecting the converter to the DC voltage intermediate circuit, and, finally, each of the AC voltage switches is closed to connect the converter to the supply system provided that no DC short circuit was able to be detected beforehand.