Abstract: An exemplary method is disclosed for disturbance current compensation for an electrical system by a disturbance current compensation device, which electrical system has a voltage source and a series circuit which is connected via a conductor in parallel with the voltage source. The series circuit has an inductance and a capacitance, with the inductance being connected in series with the capacitance via a conductor. To compensate for disturbance currents, the conductor for the connection of the voltage source to the series circuit of the inductance with the capacitance, and/or the conductor of the series circuit between the inductance and the capacitance, can be surrounded by a ring (e.g., a portion of the conductor can be substantially surrounded by the ring) which can be magnetized. The ring includes an air gap of the disturbance current compensation device. A compensation voltage can be applied by magnetization of the ring.

Abstract: A method for operating a traction converter circuit for coupling to an electric DC voltage network is stated, where the traction converter circuit comprises a network converter, which network converter on the DC voltage side is connected with a DC voltage circuit, wherein the DC voltage circuit can be switched to the electric DC voltage network, a transformer with a primary winding and a secondary winding, wherein the network converter on the alternating voltage side is connected with the primary winding of the transformer, a converter unit, which converter unit on the alternating voltage side is connected with the secondary winding of the transformer and where the network converter is controlled by means of a predeterminable network converter control signal (SN) for the setting of the network converter alternating voltage (UG).

Abstract: An exemplary method is disclosed for disturbance current compensation for an electrical system by a disturbance current compensation device, which electrical system has a voltage source and a series circuit which is connected via a conductor in parallel with the voltage source. The series circuit has an inductance and a capacitance, with the inductance being connected in series with the capacitance via a conductor. To compensate for disturbance currents, the conductor for the connection of the voltage source to the series circuit of the inductance with the capacitance, and/or the conductor of the series circuit between the inductance and the capacitance, can be surrounded by a ring (e.g., a portion of the conductor can be substantially surrounded by the ring) which can be magnetized. The ring includes an air gap of the disturbance current compensation device. A compensation voltage can be applied by magnetization of the ring.

Abstract: A method for operating a traction converter circuit for coupling to an electric DC voltage network is stated, where the traction converter circuit comprises a network converter, which network converter on the DC voltage side is connected with a DC voltage circuit, wherein the DC voltage circuit can be switched to the electric DC voltage network, a transformer with a primary winding and a secondary winding, wherein the network converter on the alternating voltage side is connected with the primary winding of the transformer, a converter unit, which converter unit on the alternating voltage side is connected with the secondary winding of the transformer and where the network converter is controlled by means of a predeterminable network converter control signal (SN) for the setting of the network converter alternating voltage (UG).

Abstract: A method and apparatus for balancing a three point DC voltage intermediate circuit involves a converter circuit which influences an electrical power flow in a three point DC voltage intermediate circuit. An intermediate circuit voltage mean value is formed from a first intermediate circuit voltage across a first capacitor, and from a second intermediate circuit voltage across a second capacitor. Based on an intermediate circuit voltage mean value exceeding a threshold value, the first capacitor is connected by means of the converter circuit to an energy store, and the energy store is then connected by means of the converter circuit to the second capacitor. If the threshold value is significantly undershot, the second capacitor is connected to the energy store by means of the converter circuit, and the energy store is then connected to the first capacitor by means of the converter circuit.

Abstract: A method is specified for operating a transformer (1) from a drivable voltage source (2), in which the voltage source, (2) produces an output voltage (uA) for feeding active power and/or a reactive component via the transformer (1) into an electrical AC voltage supply network (3), and an output current (iA) from the voltage source (2) is monitored for a maximum permissible value (iAmax) in which the magnetic flux (&phgr;) of the transformer (1) is determined continuously, and, when the maximum permissible value (iAmax) of the output current (iA) is exceeded, the voltage source (2) is disconnected from the transformer (1).

Abstract: A method is specified for operating a transformer (1) from a drivable voltage source (2), in which the voltage source (2) produces an output voltage (uA) for feeding active power and/or a reactive component via the transformer (1) into an electrical AC voltage supply network (3), and an output current (iA) from the voltage source (2) is monitored for a maximum permissible value (iAmax), in which the magnetic flux (&phgr;) of the transformer (1) is determined continuously, and, when the maximum permissible value (iAmax) of the output current (iA) is exceeded, the voltage source (2) is disconnected from the transformer (1).

Abstract: A method is specified for balancing a three-point DC voltage intermediate circuit (1), in which a converter circuit (2), which is connected to a first capacitor (C1) and to a second capacitor (C2) in the three-point DC voltage intermediate circuit (1), influences the electrical power flow in the three-point DC voltage intermediate circuit (1), and in which an intermediate circuit voltage mean value ({overscore (UDC)}) is formed from a first intermediate circuit voltage (UDC1), which is present across the first capacitor (C1), and from a second intermediate circuit voltage (UDC2), which is present across the second capacitor (C2).