Abstract: A modular multilevel converter includes a plurality of submodules, each having at least two electronic switching elements, an electric energy store, two submodule connections, a bypass switch bridging the submodule, and a communication element communicating with a communication apparatus. A method for operating the modular multilevel converter includes ascertaining that the submodules have a defective submodule so that the communication element in the defective submodule does not communicate with the communication apparatus, determining whether a present arm current resulting from an operating point of the modular multilevel converter is below a predetermined threshold value, and generating or amplifying a converter-internal circular current with the defective submodule if the arm current resulting from the operating point is below the predetermined threshold value. A modular multilevel converter is also provided.

Abstract: A converter has module devices each with a series connection of at least two partial modules being electrically connected in series. A central device is configured to switch module control devices, in which a sum of the transmitted voltage values or the transmitted sum value reaches a predefined voltage threshold, into a second charging phase of a charging operation by transmitting a first voltage specification relating to switched-off partial modules and a second voltage specification relating to switched-on partial modules to the module control devices. The module devices are configured to meet the first and second voltage specifications by setting none, one or more of the communication-capable partial modules thereof into a switched-on operating state and none, one or more of the other communication-capable partial modules thereof into a switched-off operating state, and to continue the charging of the energy stores which are in the switched-on and blocked operating state.

Abstract: A modular multilevel converter includes a plurality of submodules, each having at least two electronic switching elements, an electric energy store, two submodule connections, a bypass switch bridging the submodule, and a communication element communicating with a communication apparatus. A method for operating the modular multilevel converter includes ascertaining that the submodules have a defective submodule so that the communication element in the defective submodule does not communicate with the communication apparatus, determining whether a present arm current resulting from an operating point of the modular multilevel converter is below a predetermined threshold value, and generating or amplifying a converter-internal circular current with the defective submodule if the arm current resulting from the operating point is below the predetermined threshold value. A modular multilevel converter is also provided.

Abstract: A system contains a double fed induction machine having a stator and a rotor, a fly wheel coupled to the rotor, and a control device for providing a rotor voltage and a rotor current to the rotor. The control device is connected to the rotor and the stator and is capable of generating the rotor voltage and rotor current in response to an electrical signal that is applied to the stator. The control device has a multilevel converter and a control unit for controlling the multilevel converter.

Abstract: A method for precharging half bridge modules and full bridge modules of a modular multilevel converter includes providing the modular multilevel converter with at least one phase module branch with half bridge modules and full bridge modules connected electrically in a series circuit, and each of the half bridge modules and full bridge modules having at least first and second module connections, two electronic switching elements and an electrical energy store. In a first charging phase after connecting the multilevel converter to an energy supply network with the electronic switching elements of the half bridge modules and the full bridge modules not actuated, the energy stores of the half bridge modules and the full bridge modules are charged in an uncontrolled manner. In a second charging phase, the electronic switching elements of at least some full bridge modules are actuated such that the half bridge modules are charged further.

Abstract: A method is provided for operating a converter arrangement having a modular multilevel converter which includes at least one series circuit of double-pole switch modules, of which at least one first switch module is a full bridge switch module including controllable semiconductor switches and an energy storage device. The switches and the energy storage device are connected to one another in a full bridge circuit. After one of the semiconductor switches in the first switch module has been found to be defective, the first switch module continues to be operated as a half bridge switch module. A converter arrangement for carrying out the method is also provided.

Abstract: A system contains a double fed induction machine having a stator and a rotor, a fly wheel coupled to the rotor, and a control device for providing a rotor voltage and a rotor current to the rotor. The control device is connected to the rotor and the stator and is capable of generating the rotor voltage and rotor current in response to an electrical signal that is applied to the stator. The control device has a multilevel converter and a control unit for controlling the multilevel converter.

Abstract: A transmission device transmits energy between multiple electrical energy networks, each providing a multi-phase connection voltage at a network frequency for electrical energy supply. The transmission device contains multi-phase multi-stage rectifiers and a control device, which adjusts the transmission of energy into at least one energy-receiving energy network according to an input by controlling the multi-stage rectifiers. The multi-stage rectifiers are each connected to one of the energy networks and to one another via at least one multi-phase transformer. Electrical energy flows via the transformer at a predefined transmission frequency from at least one energy-emitting energy network into at least one energy-receiving energy network. The transmission frequency is, in particular, multiple times the network frequency.

Abstract: A transmission device transmits energy between multiple electrical energy networks, each providing a multi-phase connection voltage at a network frequency for electrical energy supply. The transmission device contains multi-phase multi-stage rectifiers and a control device, which adjusts the transmission of energy into at least one energy-receiving energy network according to an input by controlling the multi-stage rectifiers. The multi-stage rectifiers are each connected to one of the energy networks and to one another via at least one multi-phase transformer. Electrical energy flows via the transformer at a predefined transmission frequency from at least one energy-emitting energy network into at least one energy-receiving energy network. The transmission frequency is, in particular, multiple times the network frequency.