Abstract: The present disclosure relates to a method for controlling a converter, in particular power converter of a wind power installation. The converter has a plurality of, preferably parallel, converter modules. The method includes the following steps: driving a first converter module, such that the converter module generates a first electrical AC current in a first switch position, driving a second converter module, such that the converter module generates a second electrical AC current in a second switch position, superposing the first electrical AC current and the second electrical AC current to form a total current, detecting the total current of the converter, determining a virtual current depending on the first and second switch positions, and changing the first switch position of the first converter module and/or the second switch position of the second converter module depending on the total current and the virtual current.

Abstract: A method for generating an alternating electric current is provided. The method includes generating a plurality of component currents, superposing the component currents to form a summation current. Each component current is modulated by voltage pulses and the voltage pulses for each component current are generated by a component switching device by virtue of the component switching device generating the voltage pulses by switching between different input voltages. The method includes specifying a tolerance band for the summation current having an upper and a lower tolerance limit, where the summation current is detected and the switching of each component switching means is controlled to generate the voltage pulses for modulating the component current depending on the detected summation current with respect to the tolerance band. The plurality of component switching devices are switched at least partly or predominantly in a manner asynchronous with respect to one another.

Abstract: The present disclosure relates to a method for controlling a converter, in particular power converter of a wind power installation. The converter has a plurality of, preferably parallel, converter modules. The method includes the following steps: driving a first converter module, such that the converter module generates a first electrical AC current in a first switch position, driving a second converter module, such that the converter module generates a second electrical AC current in a second switch position, superposing the first electrical AC current and the second electrical AC current to form a total current, detecting the total current of the converter, determining a virtual current depending on the first and second switch positions, and changing the first switch position of the first converter module and/or the second switch position of the second converter module depending on the total current and the virtual current.

Abstract: An X-ray source arrangement (10) for generating X-ray radiation (102), a method for operating the X-ray source arrangement (10), and an X-ray imaging apparatus (100) are provided. The X-ray source arrangement (10) comprises an X-ray tube (22), a converter arrangement (16) with an inverter (18) and a resonant converter (20) for providing a source voltage to the X-ray tube (22), a pre-controller (12), and a modulator (14). The pre-controller (12) is configured for determining a reference duty ratio (r, 26) of the resonant converter (20) as a continuous function of time based on a mathematical model of the resonant converter (20), and for providing a control signal (13) correlating with the reference duty ratio (r, 26) to the modulator (14). The modulator (14) is configured for determining a switching signal (15) based on the control signal (13), and for providing the switching signal (15) to the inverter (18) of the converter arrangement (16) for actuating the inverter (18).

Abstract: A method for generating an alternating electric current is provided. The method includes generating a plurality of component currents, superposing the component currents to form a summation current. Each component current is modulated by voltage pulses and the voltage pulses for each component current are generated by a component switching device by virtue of the component switching device generating the voltage pulses by switching between different input voltages. The method includes specifying a tolerance band for the summation current having an upper and a lower tolerance limit, where the summation current is detected and the switching of each component switching means is controlled to generate the voltage pulses for modulating the component current depending on the detected summation current with respect to the tolerance band. The plurality of component switching devices are switched at least partly or predominantly in a manner asynchronous with respect to one another.

Abstract: An X-ray source arrangement (10) for generating X-ray radiation (102), a method for operating the X-ray source arrangement (10), and an X-ray imaging apparatus (100) are provided. The X-ray source arrangement (10) comprises an X-ray tube (22), a converter arrangement (16) with an inverter (18) and a resonant converter (20) for providing a source voltage to the X-ray tube (22), a pre-controller (12), and a modulator (14). The pre-controller (12) is configured for determining a reference duty ratio (r, 26) of the resonant converter (20) as a continuous function of time based on a mathematical model of the resonant converter (20), and for providing a control signal (13) correlating with the reference duty ratio (r, 26) to the modulator (14). The modulator (14) is configured for determining a switching signal (15) based on the control signal (13), and for providing the switching signal (15) to the inverter (18) of the converter arrangement (16) for actuating the inverter (18).

Abstract: In a method for generating with a modular multilevel power converter (M2C) having a plurality of sub-modules a frequency-variable output voltage, the sub-modules are switched on and off to generate from an input voltage discrete voltage steps approximating an approximately sinusoidal alternating output voltage having a first angular frequency located between a zero frequency and a second angular frequency, and the input voltage is controlled or regulated as a function of the first angular frequency so as to be located between a lower angular frequency, which is equal to or greater than the zero frequency, and a third angular frequency, such that the input voltage increases with increasing first angular frequency, thereby reducing capacitor complexity in the power converter.

Abstract: A method for generating an alternating electric current is provided. In the method, multiple partial currents are generated and superimposed into a total current. Each of the partial currents is generated using a modulation method. The modulation method uses a tolerance band method having tolerance limits that are changeable.

Abstract: A method for operating a multi-phase modular power inverter having DC input terminals and AC phase voltage output terminals connected to a load, phase modules connected between the DC input terminals, with each phase module composed of valve arms connected in series at a connection point forming an AC phase voltage output terminal which is connected to a load, each valve arm having a plurality of power inverter cells with turn-off semiconductor switches and a choke connected in series, includes controlling, with a control device, the turn-off semiconductor switches of each power inverter cell as a function of a plurality of setpoint values, wherein the setpoint values are generated such that a time-averaged energy value stored in a capacitor of a corresponding power inverter cells is predetermined by an operating point of the load and-or an operating mode of the modular multi-level power inverter.

Abstract: In a method for generating with a modular multilevel power converter (M2C) having a plurality of sub-modules a frequency-variable output voltage, the sub-modules are switched on and off to generate from an input voltage discrete voltage steps approximating an approximately sinusoidal alternating output voltage having a first angular frequency located between a zero frequency and a second angular frequency, and the input voltage is controlled or regulated as a function of the first angular frequency so as to be located between a lower angular frequency, which is equal to or greater than the zero frequency, and a third angular frequency, such that the input voltage increases with increasing first angular frequency, thereby reducing capacitor complexity in the power converter.

Abstract: A method for operating a multi-phase modular power inverter having DC input terminals and AC phase voltage output terminals connected to a load, phase modules connected between the DC input terminals, with each phase module composed of valve arms connected in series at a connection point forming an AC phase voltage output terminal which is connected to a load, each valve arm having a plurality of power inverter cells with turn-off semiconductor switches and a choke connected in series, includes controlling, with a control device, the turn-off semiconductor switches of each power inverter cell as a function of a plurality of setpoint values, wherein the setpoint values are generated such that a time-averaged energy value stored in a capacitor of a corresponding power inverter cells is predetermined by an operating point of the load and-or an operating mode of the modular multi-level power inverter.