Abb Technology Oy

Abb Schweiz Ag

Matthias Lüscher

Juerg Rauchenstein

Christian Stulz

Manuel Vetterli

Kefas Damazio-Coelho

Samuel Reist

A converter system comprises two phase modules, each phase module comprising a first converter leg and a second converter leg interconnected with a DC link, and a charging transformer for charging the DC link. The DC link comprises two capacitors connected in series between a positive point, a middle point and a negative point, each converter leg adapted for interconnecting an output with the positive point, the middle point or the negative point of the DC link. The phase modules are connected in series via outputs of the converter legs, such that a second converter leg of a lower phase module is connected with a first converter leg of a higher phase module. The charging transformer is connected to the middle point of the DC link of a highest phase module, which provides a phase output of the converter system with an output of a second converter leg. The converter system includes two converter phases, each converter phase comprising at least two series connected phase modules. At a star point of the converter phases the converter phases are star-connected via outputs of first converter legs of lowest converter modules, which are series connected with higher converter modules, whereby a module side start point of the charging transformer is connected or is not connected with the star point of the converter phases.

Charging of split DC links of a converter system

A method is disclosed in one embodiment for discharging DC link capacitors. In one form the method includes switching a first half bridge of a first converter unit to a positive state, in which its AC output is connected with its positive DC output, and simultaneously switching a second half bridge of a second converter unit to a negative state, in which its AC output is connected with its negative DC output, such that a DC link capacitor of the first converter unit and a DC link capacitor of the second converter unit are interconnected oppositely to each other and discharged via the electrical filter.

Discharging DC link capacitors in an NPC converter

A method, a controller unit for a bridge rectifier, and a bridge rectifier system are disclosed for detecting a shorted diode in a bridge rectifier. The method can include determining a phase-to-phase voltage between two phase inputs of the bridge rectifier, wherein a phase input is provided between the two series connected diodes of the respective phase, and indicating a shorted diode fault by determining whether the phase-to-phase voltage is zero for more than a commutation time of the bridge rectifier.

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Gontenschwil, Switzerland

Matthias Lüscher