Abstract: An exemplary converter circuit has a converter unit with plural actuatable power semiconductor switches, and the DC voltage side of which is connected to a capacitive energy storage circuit. The capacitive energy storage circuit has at least one capacitive energy store and at least one snubber network for limiting the rate of current or voltage rise on the actuatable power semiconductor switches of the converter unit. In order to reduce undesirable oscillations in an overcurrent in the capacitive energy storage circuit, the capacitive energy storage circuit has at least one passive nonactuatable damping unit having a unidirectional current-flow direction, where the passive nonactuatable damping unit has a diode and a damping resistor.

Abstract: A polyphase converter circuit having p?3 phases (R, Y, B) and a converter circuit element provided for each phase (R, Y, B) is specified, each converter circuit element having a rectifier unit, a DC voltage circuit which is connected to the rectifier unit and an inverter unit which is connected to the DC voltage circuit. In addition, a first AC voltage output of each inverter unit forms a phase connection, and second AC voltage outputs of the inverter units are star-connected. In order to produce harmonics which are as low as possible with respect to the fundamental of the voltage and the current of an electrical AC voltage system which is connected on the input side to the converter circuit, n transformers are provided, each having a primary winding and m three-phase secondary windings, where n?2 and m?3.

Abstract: A polyphase converter circuit having p?3 phases (R, Y, B) and a converter circuit element provided for each phase (R, Y, B) is specified, each converter circuit element having a rectifier unit, a DC voltage circuit which is connected to the rectifier unit and an inverter unit which is connected to the DC voltage circuit. In addition, a first AC voltage output of each inverter unit forms a phase connection, and second AC voltage outputs of the inverter units are star-connected. In order to produce harmonics which are as low as possible with respect to the fundamental of the voltage and the current of an electrical AC voltage system which is connected on the input side to the converter circuit, n transformers are provided, each having a primary winding and m three-phase secondary windings, where n?2 and m?3.