Abstract: Disclosed is a method for operating a three-phase inverter on a three-phase load. The three-phase inverter has a direct voltage intermediate circuit, at least one three-phase bridge circuit, and at least one control unit for controlling the bridge circuit. In the at least one bridge circuit, at least two power switches per phase are provided, which are connected in series parallel to the direct voltage intermediate circuit. Depending on predefined target voltage values of the three phases of the inverter, the power switches of each individual phase are actuated via the control unit such that a three-phase alternating voltage is generated on the three-phase load via switching operations of the power switches. Very good dynamic control behaviour can be achieved despite cost-effective dimensioning of the IGBT power switches of the three-phase bridge circuit.

Abstract: A device for generating electrical energy, in particular a wind turbine, having at least one generator is disclosed. The generator provides electrical energy by means of multi-phase, machine-side connection means and is connected to at least one converter having a DC link via the multi-phase, machine-side connection means. A method for operating a device for generating electrical energy, in particular a wind turbine, is also disclosed. The object of providing a device for generating electrical energy, in particular a wind turbine, which reliably avoids the development of surges despite parasitic inductances and capacitances by means of the machine-side multi-phase connection means is achieved in that means for attenuating at least one series resonance in the zero sequence of the machine-side connection means are provided between generator and converter.

Abstract: Provided is an apparatus for delivering electrical power, in particular for delivering regeneratively produced electrical power, which has at least one converter and at least one filter for matching the delivery of power by the converter to a load impedance. Also provided is a method for operating the apparatus for delivering electrical power which allows improved monitoring of the functioning of the filters or mains filters and which uses means for determining at least one filter current in at least one filter, which means are designed in such a manner that said means make it possible to determine the at least one filter current during operation of the apparatus. Comparison means are provided and generate an error information signal using the desired value and actual value of the filter current and a predefinable error criterion.

Abstract: Provided is an apparatus for delivering electrical power, in particular for delivering regeneratively produced electrical power, which has at least one converter and at least one filter for matching the delivery of power by the converter to a load impedance. Also provided is a method for operating the apparatus for delivering electrical power which allows improved monitoring of the functioning of the filters or mains filters and which uses means for determining at least one filter current in at least one filter, which means are designed in such a manner that said means make it possible to determine the at least one filter current during operation of the apparatus. Comparison means are provided and generate an error information signal using the desired value and actual value of the filter current and a predefinable error criterion.

Abstract: The invention relates to a method to control power output of a doubly-fed induction machine to a grid including the steps of measuring grid voltage and grid current in a three phase coordinate system, transforming grid voltage and grid current into a stator frame coordinate system, decomposing the grid voltage and grid current in the stator frame coordinate system in a positive sequence system and in a negative sequence system, calculating active and reactive power in the positive and negative sequence system, and controlling active and reactive power in the positive and negative sequence system.

Abstract: The invention relates to a device and method for controlling a double-fed asynchronous machine (4), preferably for a power plant, in particular for a wind or water power plant. The device includes an indirect converter (6) which is connected on the rotor side to the double-fed asynchronous machine (4). The indirect converter (6) includes a rotor-side converter (20) and a line-side converter (24). At least one control element (8) is provided for controlling the indirect converter (6). At least one software-based and/or hardware-based damping element (40, 46, 48, 120) is provided which has changeable damping characteristics.

Abstract: The invention relates to a method and a device for operating an asynchronous motor (1) with double feeds, having a stator (1a) connected to a grid and a rotor (1b) connected to an inverter (6), said inverter (6) being designed such that it impresses a target value for an electrical variable in the rotor (1b). In a method according to the invention, after detecting a transient grid voltage change, a target value for the electrical variable determined from at least the rotor flux and the stator flux is impressed in the rotor (1b) such that an active reduction in the torque occurring during the transient grid voltage change is achieved. The target value of the electrical variable is preferably determined from a suitable weighting of the stator flux, rotor flux, stator voltage, stator current, rotor current, and, if available as a measured variable, stator voltage.

Abstract: The invention relates to a device and method for controlling a double-fed asynchronous machine (4), preferably for a power plant, in particular for a wind or water power plant. The device includes an indirect converter (6) which is connected on the rotor side to the double-fed asynchronous machine (4). The indirect converter (6) includes a rotor-side converter (20) and a line-side converter (24). At least one control element (8) is provided for controlling the indirect converter (6). At least one software-based and/or hardware-based damping element (40, 46, 48, 120) is provided which has changeable damping characteristics.

Abstract: The invention relates to a method to control power output of a doubly-fed induction machine to a grid including the steps of measuring grid voltage and grid current in a three phase coordinate system, transforming grid voltage and grid current into a stator frame coordinate system, decomposing the grid voltage and grid current in the stator frame coordinate system in a positive sequence system and in a negative sequence system, calculating active and reactive power in the positive and negative sequence system, and controlling active and reactive power in the positive and negative sequence system.

Abstract: The invention relates to a method and a device for operating an asynchronous motor (1) with double feeds, having a stator (1a) connected to a grid and a rotor (1b) connected to an inverter (6), said inverter (6) being designed such that it impresses a target value for an electrical variable in the rotor (1b). In a method according to the invention, after detecting a transient grid voltage change, a target value for the electrical variable determined from at least the rotor flux and the stator flux is impressed in the rotor (1b) such that an active reduction in the torque occurring during the transient grid voltage change is achieved. The target value of the electrical variable is preferably determined from a suitable weighting of the stator flux, rotor flux, stator voltage, stator current, rotor current, and, if available as a measured variable, stator voltage.